Patient and parent perceptions of myopia modalities

PurposeThis study compared quality of life (QoL) of myopic adults and children who were established spectacle, soft contact lens (SCL), or orthokeratology (OK) wearers as well as parent/child responses using Pediatric Refractive Error Profile 2 (PREP2).MethodsForty-eight adults (aged 18–26 years), 49 children (aged 9–17 years), and the children’s parent, completed PREP2, with 7 subscales (symptoms, vision, activities, appearance, peer perception, handling, and overall). Adults and children must have worn their correction for at least three years. Parents were asked to answer how they thought their child would answer. Scores were compared between age groups, among correction groups, and between children and their parents using non-parametric ANOVA, Mann-Whitney U and Wilcoxon Signed-Rank tests, as appropriate. Post-hoc pairwise comparisons among correction groups were conducted with Bonferroni adjustment.ResultsAverage age of adults was 22 ± 2 and children was 14 ± 2 years, and duration of correction use was 8 ± 3 for adults and 5 ± 2 years for children (both p < 0.01). Adult OK wearers were more satisfied with vision (p = 0.04), activities (p < 0.001) and overall (p = 0.03) compared to spectacle wearers. Children OK wearers reported higher scores for activities than SCL (p = 0.048) and spectacle wearers (p < 0.001). Parents of contact lens wearers reported higher perceived QoL for activities (OK p < 0.001; SCL p = 0.02), handling (OK p = 0.02; SCL p < 0.001), appearance (SCL p = 0.001), and overall (OK p = 0.001; SCL p < 0.001) subscales than parents of child spectacle wearers.ConclusionActivity-driven children and adults perceive significant benefits from OK over spectacles. Parents’ perceptions did not align with their children’s perceptions of their correction.     

Clinical factors associated with positive corneal culture in suspected microbial keratitis

AimsDetermine demographic and clinical characteristics associated with positive culture in suspected microbial keratitis.MethodsRetrospective audit of patients that had corneal scrapings between October 1999-September 2004 at Princess Alexandra Hospital. Clinical information was gathered from medical records, smear and culture results from the local microbiology database. Univariate and multivariate analyses of variables associated with positive cultures and calculation of population attributable risk percentage (PAR).ResultsUnivariate analysis showed that positive cultures were associated with patients over 60 years (81% vs 55%; p < 0.001), presenting visual acuity (VA) of 6/24 or worse (74% vs 57%; p = 0.012) or contact lens-related keratitis (CLK 77% vs 62%; p = 0.08). Analysis of patients’ clinical presentation showed that positive culture was associated with a central epithelial defect (74% vs 57%; p = 0.012), anterior chamber reaction of 2 + cells or worse (73% vs 56%; p = 0.03), an epithelial defect of 2 mm or more in diameter (71% vs 50%; p = 0.006) or no prior treatment with antibiotics (68% vs 56%; p = 0.053). Multivariate analysis showed the independent variables associated with positive cultures were VA of 6/24 or worse on presentation, contact lens-related keratitis, age greater than 60 years, an anterior chamber reaction of 2 + cells or worse and no prior treatment with antibiotics. The factor with the highest attributable risk (PAR%) for a positive corneal scraping was VA of 6/24 or worse on presentation (21%).ConclusionsIn this series positive cultures were associated with poor presenting VA contact lens keratitis (CLK), older age, anterior chamber reaction and no prior treatment with antibiotics.     

Changes in corneal thickness,corneal volume,and densitometry after long-term orthokeratology wear

PurposeTo investigate changes in the corneal volume, corneal densitometry and pachymetry of young myopes wearing over-night orthokeratology (OK) contact lenses.MethodsThe medical records of 28 right eyes of young myopes wearing OK between 2013 and 2018 were reviewed retrospectively. The baseline refractive error, best corrected visual acuities at baseline and uncorrected visual acuity at the most recent visit were recorded. Corneal volume of the central 10 mm cornea; densitometry at central, nasal and temporal cornea; and pachymetry along the horizontal and vertical meridians were collected from the Pentacam® HR at baseline, after one night of lens wear, and at the latest visit.ResultsThe mean age of subjects was 12.03 ± 3.80 years at the time of OK lens fitting and wore OK overnight for a mean duration of 666 days (range 206–1736 days). The baseline spherical equivalent refractive error was ?3.03 ± 1.56 D (range ?1.00 to ?6.00 D). The corneal volume increased significantly after OK wear (p = 0.001). Corneal densitometry increased after OK wear, but the change did not reach statistical significance (p = 0.113). Pachymetry in the central cornea did not change significantly across all visits (p > 0.05) but increased significantly in the mid-peripheral regions of the cornea. Baseline refractive error was not found to be correlated with the changes in corneal volume, corneal densitometry, or pachymetry.ConclusionThe increase in corneal volume and densitometry and no significant change in the central corneal thickness may indicate the presence of corneal oedema from long-term OK wear. The baseline refraction was not correlated with the changes in corneal volume, densitometry or pachymetry.     

Improved contact lens fitting after corneal cross-linking in eyes with progressive keratoconus

ObjectivesThe study aimed to assess the possible effects of corneal cross-linking (CXL) on contact lens (CL) fitting in patients with progressive keratoconus who initially had CL intolerance.MethodsA retrospective review was performed of the medical records of patients who had stopped CL wear due to discomfort prior to CXL and who were fitted with CLs after CXL. All eyes were evaluated pre- and 1, 6, 12, 24 months postoperatively. Data collected included pre- and post-CXL refraction, corneal topographic data, uncorrected visual acuity, and best-corrected visual acuity (BCVA). CL comfort was evaluated using the Likert scale post-CXL.ResultsA total of 20 eyes from 14 patients were included in the study. Preoperative Kmax values significantly decreased by 2.8 D at 6 months and by 4.1 D at 12 months after CXL (p < 0.001 for both). CLs were prescribed on average 12 ± 2.5 months after CXL. The mean duration of successful CL wear was 10.4 ± 2.8 months during the follow-up period. Subjective CL comfort scores were satisfactory post-CXL.ConclusionCXL not only halts the progression of keratoconus but may also improve CL tolerance by providing a more regular shaped cornea in these patients. Ongoing corneal topographic changes in the late postoperative period after CXL may have a positive effect on CL fitting.     

A machine learning-based algorithm for estimating the original corneal curvature based on corneal topography after orthokeratology

ObjectiveTo estimate the original corneal curvature after orthokeratology by applying a machine learning-based algorithm.MethodsA total of 497 right eyes of 497 patients undergoing overnight orthokeratology for myopia for more than 1 year were enrolled in this retrospective study. All patients were fitted with lenses from Paragon CRT. Corneal topography was obtained by a Sirius corneal topography system (CSO, Italy). Original flat K (K1) and original steep K (K2) were set as the targets of calculation. The importance of each variable was explored by Fisher’s criterion. Two machine learning models were established to allow adaptation to more situations. Bagging Tree, Gaussian process, support vector machine (SVM), and decision tree were used for prediction.ResultsK2 after one year of orthokeratology (K2_after) was most important in the prediction of K1 and K2. Bagging Tree performed best in both models 1 and 2 for K1 prediction (R = 0.812, RMSE = 0.855 in model 1 and R = 0.812, RMSE = 0.858 in model 2) and K2 prediction (R = 0.831, RMSE = 0.898 in model 1 and R = 0.837, RMSE = 0.888 in model 2). In model 1, the difference was 0.006 ± 1.34 D (p = 0.93) between the predictive value of K1 and the true value of K1 (K1_before) and was 0.005 ± 1.51 D(p = 0.94) between the predictive value of K2 and the true value of K2 (K2_before). In model 2, the difference was −0.056 ± 1.75 D (p = 0.59) between the predictive value of K1 and K1_before and was 0.017 ± 2.01 D(p = 0.88) between the predictive value of K2 and K2_before.ConclusionBagging Tree performed best in predicting K1 and K2. Machine learning can be applied to predict the corneal curvature for those who cannot provide the initial corneal parameters in the outpatient clinic, providing a relatively certain degree of reference for the refitting of the Ortho-k lenses.     

Profile of pediatric aphakics over 10 years in a tertiary eye care – A retrospective study

AimTo investigate the outcome of contact lens (CL) fitting in aphakic children following lensectomy for congenital cataract.MethodRetrospective data of 205 aphakic children who visited for CL fitting following lensectomy from 2008 to 2018 were collected. Data includes the demographic details, CL parameters in first and last visit, hours of CL wear, reason for discontinuation of CL, surgical procedures underwent and years of follow up.Results205 (148 unilateral and 57 bilateral) aphakic children comprised of age group, < 1 month (n = 48), 1–3 months (n = 37), 3–6 months (n = 68), 6–12 months (n = 10), >12 months (n = 42). 173/205(84.39%) children were fitted with rigid gas permeable (RGP) and 32/205(15.6%) were fitted with soft CL at their first visit. 10 children had shifted to soft CL in their follow-up visits due to intolerance to RGP. 97/205(47.32%) children continued CL (55RGP, 42SCL) till the last follow-up for 2.17 ± 2.36 years and wore lens for 3.7 ± 3.65 h per day. Number of lenses replaced was 2 lenses (median) and maximum of 9 lenses over a period of 1–8 visits. The maximum visual acuity achieved was up to 0.2 log Mar units at the youngest age of 4 years on successful CL wear. 60/205(29.26%) children discontinued lenses at different follow-up visits due to IOL implantation(n = 28),using spectacles due to handling difficulty, child uncooperative to lens wear and lens fitting issues(n = 32). 48/205(23.41%) were lost to follow-up after the first visit. The average K (7.46 ± 0.43 mm) showed significant correlation to lens base curve in first visit (7.48 ± 0.41 mm) whereas flat K (7.71 ± 0.38 mm) showed significant correlation in the last visit (7.46 ± 0.39 mm) (p < 0.005). This was well described by a significant diameter change of 8.68 ± 0.31 mm to 9.42 ± 1.77 mm (p < 0.005) at the first and last visit respectively. The refractive error showed a significant difference between first (27.96 ± 5.33D) and last visit (21.97 ± 6.85D) (p < 0.005).ConclusionThis study witnessed successful contact lens wear in only half of the children. The visual rehabilitation following lensectomy depends on right CL choice and close follow-up.     

Optical quality and intraocular scattering assessed with a double-pass system in eyes with contact lens induced corneal swelling

PurposeTo evaluate the impact of contact lens (CL)-induced corneal swelling on the optical quality of the eye by means of the double-pass technique.MethodsMeasurements of 6 healthy subjects were obtained in 5 visits over 1 week, at baseline and after sleeping with 4 different CLs of +0.50 D, +2.00 D, +5.00 D and +8.00 D (Acuvue2), randomly fitted on 4 different days. The control eye wore no CL. Corneal pachymetry and optical quality of the eye (OQAS, Visiometrics) were measured once at baseline and at three interval times in the follow-up visits: immediately after CL removal, and 1 and 2 h after CL removal. Optical quality was evaluated by means of the Strehl ratio and OQAS values at 100%, 20% and 9% contrasts. Intraocular scattering was evaluated with the objective scatter index (OSI).ResultsMean overnight swelling was 5.98 ± 4.29% in CL-eyes versus 0.30 ± 0.78% in control eyes (p < 0.01). Corneal swelling was maximal immediately after CL removal and decreased with time (p < 0.01). A significant worsening in all optical quality parameters and a significant increase of the OSI were found in eyes with corneal swelling (p < 0.05). Two hours after CL removal there were no statistically significant differences (p > 0.05) between CL-eyes and control eyes in any of the measured parameters.ConclusionsCorneal swelling has a significant impact on the optical quality of the eye and on intraocular scattering as assessed with the double-pass technique.     

Progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses

PurposeTo investigate the rate of progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses (pancorneal RGP-CL) compared to non-pancorneal RGP-CL. We also evaluated alterations in anterior chamber parameters with the progression of keratoconus and investigated the location of the cone in eyes with keratoconus.MethodsThe current study was a retrospective study including patients with clinically evident keratoconus from the outpatient clinic from the Department of Ophthalmology of the Erasmus Medical Center, Rotterdam, the Netherlands. Medical history and contact lens characteristics were documented. All participants underwent ophthalmic examination including corneal topography. Corneal topography was repeated at one of the consecutive visits of the patient. Patients were divided into two groups: those wearing pancorneal RGP-CL and those wearing other contact lens types. As a measure of progression of keratoconus differences in corneal topography parameters between both groups were compared.ResultsA total of 82 patients were included of which 42 had follow-up (mean 17.8 months) data. We found a significant difference in progression between eyes fitted with and without pancorneal RGP-CL (K-flat: p = 0.09, K-steep: p = 0.02, K-mean: p = 0.02, and K-minimum: p = 0.04). Compared with eyes fitted without pancorneal RGP-CL no significant difference in K-values was found for eyes fitted with pancorneal RGP-CL during follow-up. Furthermore, a significant decrease in anterior chamber volume (p < 0.001) and corneal volume (p = 0.008) was found during follow-up. In 86.6% the location of the cone was located infero-temporal.ConclusionsPancorneal RGP-CL have a better effect on stabilizing progression of keratoconus than non-pancorneal RGP-CL. The finding of an infero-temporal location of the cone in keratoconic corneas may improve results of contact lens fitting and surgical management.     

Crystalline lens thickness change is associated with axial length elongation and myopia progression in orthokeratology

AimsConsidering individual variability in regards to the effects of orthokeratology (ortho-k) on myopia progression and controversies regarding the precise underlying mechanism, the aim of this study was to investigate several ocular measurements associated with axial length (AL) growth in children wearing ortho-k lenses.MethodsIn this retrospective chart review, medical records of 53 Chinese children who wore ortho-k lenses over the course of 12 months were reviewed. Baseline variables included age at initiation of ortho-k wear, refractive error (spherical equivalent, SE), central corneal thickness (CCT), and flat and steep keratometry of corneal principal meridians. The change of anterior chamber depth (ACD) and the change of crystalline lens thickness (CLT) between baseline and the 12-month follow-up were also analyzed. The contributions of all analyzed variables to AL change were assessed using univariate and multivariate regression analyses.ResultsInitially, the results of paired t-test showed that CLT and AL were significantly increased after 12 months of ortho-k wear compared with that at baseline (P = 0.001 and < 0.001). The ACD did not change significantly after 12 months compared with that at baseline (P = 0.491). Subsequently, univariate analyses showed that a reduced rate of AL elongation was found in children who were older age at initiation of ortho-k wear (P = 0.028), had greater SE (higher degree of myopia) at baseline (p = 0.006), had thicker CCT at baseline (P = 0.04), and had greater increase of CLT (P = 0.001) in 12 months. At last, only greater SE (higher degree of myopia) and greater increase of CLT were associated with smaller increases of AL in multivariable analyses, (P = 0.003 and 0.001).ConclusionsBoth CLT and AL were significantly increased in children with overnight ortho-k wear after 12 months of follow-up. Greater baseline SE and greater increase of CLT were associated with less increase in AL during ortho-k wear in children with myopia.     

Clinical evaluation of different types of contact lenses in keratoconus management

PurposeTo compare the clinical and topographical findings of the keratoconus patients according to the prescribed contact lens type and to investigate the effects of corneal collagen cross-linking (CXL) and cone location on lens selection.MethodsThe records of 301 eyes of 195 keratoconus patients who were prescribed contact lenses were analyzed retrospectively. The eyes were grouped according to the lens type: Soft toric contact lens (STCL), rigid gas-permeable contact lens (RGPCL), hybrid contact lens (HCL) and mini-scleral contact lens (MSCL). The history of having CXL, ophthalmological examination findings, and the topographical findings were compared between the groups. Brown-Forsythe, Chi-square, and post-hoc tests were used to compare the groups. Mann-Whitney U test was used for subgroup analysis. Comparison of the lens-corrected visual acuity (LCVA) and spectacle-corrected visual acuity (SCVA) levels was made with Wilcoxon signed-ranks test.ResultsThere was no significant difference between the groups regarding topographical cone location, CXL history, spherical refraction, and LCVA. The difference between spectacle-corrected visual acuity and LCVA was higher in RGPCL and MSCL groups than STCL group (p=0.01). Keratometry of RGPCL and MSCL groups were higher than STCL and HCL groups (p=0.01, p<0.001). In RGPCL group, eyes with central cones had a higher increase in visual acuity with contact lenses compared to eyes with paracentral cones (p=0.043). STCL and MSCL were mostly prescribed in mild and severe keratoconic eyes, respectively. In RGPCL group, the increase in visual acuity with contact lens was higher in eyes treated with CXL (p= <0.01).ConclusionsWhile STCL and HCL were mostly prescribed in mild keratoconus, RGPCL and MSCL were selected for moderate or advanced disease. If appropriately chosen, all types of contact lenses could result in a good visual acuity level. CXL history did not affect the prescribed lens type. Having central cone location and CXL history in RGPCL group improved visual acuity more efficiently.     

Stabilization of comfort and visual quality after the insertion of soft contact lenses

PurposeTo evaluate comfort, visual function, and in vivo wettability after the insertion of hydrogel and silicone hydrogel contact lenses for a better understanding of how long practitioners should wait for the initial evaluation of soft contact lenses.MethodsA short-term prospective, contralateral, randomized, and participant-masked study was carried out. Twenty healthy participants (25.4 ± 2.6 years) were evaluated after the insertion of two different soft contact lenses at different times (1, 5, 10, 20, 30 min). Ocufilcon D (hydrogel) and Somofilcon A (silicone hydrogel) contact lenses were randomly assigned to both eyes of the same participant. Comfort, visual function under photopic conditions in terms of high-contrast visual acuity, low-contrast visual acuity, contrast sensitivity, and in vivo wettability were measured.ResultsThere was an increase in comfort (p < 0.001), high-contrast visual acuity (p < 0.05), and contrast sensitivity (p < 0.001, only with silicone hydrogel) directly related to time after contact lens insertion. Besides, in vivo wettability suffered a statistically significant deterioration directly related to time with both contact lenses (p < 0.05). Except for comfort and contrast sensitivity, all the parameters stabilized their values 10 min after the insertion of both soft contact lenses. Additionally, in vivo wettability and visual acuity differences were found between hydrogel and silicone hydrogel contact lenses (p < 0.05).ConclusionsIt would be possible to properly evaluate high-contrast visual acuity, low-contrast visual acuity, and in vivo wettability 10 min after the insertion of both soft contact lenses.     

Improving ocular surface comfort in contact lens wearers

PurposeContact lens discomfort (CLD) is a major concern that can lead to the decreased or abandoned use of contact lenses. Contact lens users with dry eye disease are more likely to present with CLD. This study was conducted to evaluate the efficacy of a bioprotective preservative free, hypotonic, 0.15% hyaluronic acid (HA)-3% Trehalose artificial tear in managing dry eye symptoms in contact lens wearers.MethodsA prospective, single-arm, observational pilot study to evaluate the effectiveness of treatment with HA-Trehalose artificial tears in contact lens wearers (N = 33) aged 18–45 years with symptoms of ocular discomfort. Participants used a preservative-free, hypotonic HA-Trehalose artificial tear (1 drop/4 times per day) for 84 days. Participants were assessed using Visual Analogue Scale (VAS) for dry eye symptoms (pain, photophobia, dry eye sensation, blurry vision, foreign body sensation, itching, tingling/burning, and sticky eye feeling), Ocular Surface Disease Index (OSDI), Contact Lens Dry Eye questionnaire (CLDEQ-8), Berkley Dry Eye Flow-Chart (DEFC) on Day 0 and Day 84 and tear break-up time (TBUT), ocular surface staining with fluorescein and lissamine green, tear meniscus evaluation, and visual acuity on Day 0, 35, and 84.ResultsAll VAS symptoms (except tingling/burning and sticky eye feeling), OSDI, CLEDQ-8, and DEFC showed statistically significant (p < 0.05) improvement from baseline (Day 0) to Day 84. Similarly, corneal (fluorescein) and conjunctival (lissamine green) quality improved during the study (p < 0.05 at Day 84 versus baseline). Tear break-up time (TBUT), conjunctival (lissamine green) staining, and tear meniscus decreased but the changes were not statistically significant. Visual acuity did not change during the study. There were no ocular or systemic adverse events.ConclusionsThis study showed that the instillation of a preservative-free, hypotonic, HA-Trehalose artificial tear in contact lenses wearers with dry eye syndrome significantly improved symptoms and reduced associated signs such as corneal and conjunctival staining.     

Factors influencing treatment zone size in orthokeratology

PurposeThe aim of this study was to analyze the influence of corneal topography, contact lens parameters and degree of myopia on the treatment zone (TZ) and peripheral plus ring (PPR) size in orthokeratology.MethodsIn this retrospective study the topographic zones of the right eyes of 106 patients (73 female, 22.16 ± 8.96 years) were analyzed in the tangential difference map of the Oculus Keratograph 5M (Oculus, Wetzlar, Germany). Using the MB-Ruler Pro 5.4 software (MB-Softwaresolutions, Iffezheim, Germany) the horizontal, vertical, longest, shortest diameters and area of the TZ; horizontal, vertical, total diameters and width of the PPR were measured. Correlations were determined between these zones and the subjects’ baseline parameters (myopia; corneal diameter, radii, astigmatism, eccentricity, sagittal height; contact lens radii, toricity and total diameter) for three back optic zone diameter (BOZD) groups (5.5, 6.0 and 6.6 mm). A stepwise linear regression analysis was performed to test for TZ and PPR predictability.ResultsIn the group of BOZD 6.0 correlations were found between the amount of myopia and the short TZ diameter (r = −0.25, p = 0.025); the steep corneal radius and the vertical diameter (r = –0.244, p = 0.029), the longest diameter (r = −0.254, p = 0.023) and the area (r = −0.228, p = 0.042) of the TZ; the amount of astigmatism and PPR width (r = 0.266, p = 0.017); eccentricity of the steep corneal meridian and PPR width (r = –0.222, p = 0.047). BOZD correlated significantly positively with all zones (p < 0.05). The best prediction model (R² = 0.389) resulted with the TZ area as the outcome variable.ConclusionThe amount of myopia, topography and contact lens parameters influence TZ and PPR in orthokeratology. Describing the TZ by its area may provide the most accurate representation of its size.     

The effects of base curve aspheric orthokeratology lenses on corneal topography and peripheral refraction: A randomized prospective trial

BackgroundTo investigate the effects of orthokeratology (ortho-k) lenses with aspheric and spherical base curve designs on corneal refractive power (CRP) and peripheral refraction.MethodsChildren aged 8 to 12 years with myopia between −0.75 D to −4.00 D, astigmatism ≤1.00 D, and corneal astigmatism ≤1.50 D were randomly assigned to the base curve aspheric (BCA) and base curve spherical (BCS) ortho-k lens groups. CRP was assessed for the central 8 mm cornea along horizontal and vertical meridians, and peripheral refraction was measured at 10°, 20°, and 30° along the nasal and temporal retina. Primary measurements included relative corneal refractive power change (RCRPC) and relative peripheral refraction change (RPRC).ResultsThe 3-month results of the 33 and 29 subjects (right eye only) in the BCA and BCS groups, respectively, were obtained. Nonsignificant differences were found in the baseline data between the two groups (p > 0.05). At the 3-month follow-up visit, the mean RCRPC in the BCA group (2.08 ± 0.65 D) was significantly greater than that in the BCS group (1.32 ± 0.81 D) (F_1,51 = 25.25, p < 0.001). The BCA group (-1.82 ± 0.65 D) exhibited a larger absolute RPRC than the BCS group (-0.98 ± 0.54 D) (F_1,57 = 33.73, p < 0.001).ConclusionsIt was found that the BCA ortho-k lens resulted in a more aspheric treatment zone and a more myopic relative peripheral refraction (RPR) along the horizontal meridian. The more myopic RPR was contributed by a more hyperopic central refraction and a more myopic peripheral refraction in the BCA group.     

Efficacy of two silicone-hydrogel contact lenses for bandage use after photorefractive keratectomy

PurposeTo evaluate the efficacy of two silicone hydrogel (SiH) contact lenses, approved for continuous wear for one week, following photorefractive keratectomy (PRK).MethodsForty seven myopic patients (94 eyes) undergone bilateral PRK were enrolled in this prospective, double-masked, comparative study. One eye of each patient was fitted with a Lotrafilcon B lens (Ciba Vision, Duluth, US; 30-day recommended replacement) whereas the fellow eye was fitted with an Asmofilcon A lens (Menicon, Nagoya, Japan; 14-day recommended replacement). Epithelial defect size was assessed using slit lamp biomicroscopy on the day of surgery and at days 1–4 post-operatively. Uncorrected and best-corrected visual acuity and retinal straylight (C-Quant, Oculus Optigerate, Germany) were evaluated pre-operatively and one month post-operatively.ResultsAverage epithelial defect size for Asmofilcon A and Lotrafilcon B was 25.5 ± 11.0 mm² vs. 27.1 ± 9.9 mm² at day 1 (p = 0.007) and 6.3 ± 7.0 mm² vs. 9.2 ± 9.5 mm² at day 2 (p = 0.012) post-operatively. Re-epithelialization at day 3 was completed in 87.2% of the eyes fitted with Asmofilcon A lenses, compared to 74.5% with Lotrafilcon B lenses (p = 0.012). At the 3rd post-operative day 29.8% of re-epithelialized eyes showed irregular suture with Lotrafilcon B, compared to 12.8% eyes with Asmofilcon A lenses (p < 0.001). Finally, no statistically significant differences were found post-operatively between the two lenses retinal straylight (p = 0.98) and best-corrected visual acuity (p = 0.68).ConclusionsSiH lenses can be used as an effective bandage after PRK due to the limited time requested for achieving complete corneal re-epithelialization. Faster and smoother epithelial healing is provided with Asmofilcon A over Lotrafilcon B lenses.     

International multi-centre study of potential benefits of ultraviolet radiation protection using contact lenses

PurposeTo examine the effects of long-term ultraviolet radiation (UVR) blocking wearing contact lenses on ocular surface health, eye focus and macular pigment.Method210 pre-presbyopic patients were recruited from Birmingham UK, Brisbane Australia, Hong Kong China, Houston USA and Waterloo Canada (n = 42 at each site). All patients had worn contact lenses for ≥ 5 years, half (test group) of a material incorporating a UVR-blocking filter. Ocular health was assessed using slit-lamp biomicroscopy and UV autofluorescence. Accommodation was measured subjectively with a push-up test and overcoming lens-induced defocus. Objective stimulus response and dynamic measures of the accommodative response were quantified with an open-field aberrometer. Macular pigment optical density (MPOD) was assessed using heterochromatic flicker photometry (MPS II).ResultsThe two groups of participants were matched for age, sex, race, body-mass-index, diet, lifestyle, UVR exposure, refractive error and visual acuity. Limbal (p = 0.035), but not bulbar conjunctival redness (p = 0.903) was lower in eyes that had worn UVR-blocking contact lenses compared to controls. The subjective (8.0 ± 3.7D vs 7.3 ± 3.3D; p = 0.125) and objective (F = 1.255, p = 0.285) accommodative response was higher in the test group, but the differences did not reach significance. However, the accommodative latency was shorter in eyes that had worn UVR-blocking contact lenses (p = 0.003). There was no significant different in MPOD with UVR filtration (p = 0.869).ConclusionsBlocking the transmission of UVR is beneficial in maintaining the eye’s ability to focus, suggesting that presbyopia maybe delayed in long-term UVR-blocking contact lenses wearers. These lenses also provide protection to the critical limbal region.     

Effect of overnight orthokeratology lenses on tear film stability in children

PurposeTo assess the tear film surface quality after orthokeratology using an automated Medmont E300 corneal topographer.MethodsChildren who wore orthokeratology lenses for more than one year were selected in this retrospective study. Tear film disruption (TFD) and central tear film disruption (cTFD) were measured with Medmont E300 corneal topographer at initial and each follow-up visit after fitting with orthokeratology lenses, providing a nominal value from 0 (perfect) to 1 (poor). Tear film surface quality before and after ortho-k treatment was compared.Results145 children using orthokeratology lenses were observed. TFD and cTFD significantly increased at 1-day follow up (TFD, t = -17.3, P < 0.001; cTFD, t = -10.4, P < 0.001). This change remained consistent through to 12-months visit (TFD, F = 51.1, P < 0.001; cTFD, F = 28.0, P < 0.001). A sub-group of n = 11 children were discontinued for 1-month before being refit with OrthoK lenses of a different design. Similarly, there was a significant increase in TFD compared to pre-orthoK scans (0.172 ± 0.161), but this returned to baseline levels after ceasing lens wear (0.084 ± 0.059). A sub-group of monocular OrthoK wearers (n = 23) found that TFD and cTFD values increased in eyes with monocular lens-wearing but remained stable in the lateral eyes.ConclusionsObjective measurements of tear-film quality are reduced in children after fitting with orthokeratology lenses, but return to baseline after 1-month of lens cessation. It is of importance to ensure tear film surface quality is continuously monitored throughout use of orthoK lenses.     

High myopia-partial reduction orthokeratology (HM-PRO): Study design

PurposeTo report the study design and preliminary results of a pilot study, High Myopia-Partial Reduction Orthokeratology study.MethodsChildren with myopia of 6.00D or above and who satisfied the recruitment criteria were randomly assigned to partial reduction orthokeratology (PR ortho-k) and spectacle-wearing control groups. The myopia of the PR ortho-k children were partially reduced using custom made 4-zone ortho-k lenses of target 4.00D. Residual refractive errors were corrected with single vision spectacles. Control subjects were fully corrected with single vision spectacles. PR ortho-k subjects were also required to return for assessment after the first overnight lens wear, and one week and one month after lens wear.ResultsFifty-two eligible subjects were randomly assigned to PR ortho-k group (n = 26) and control group (n = 26). The median age of each group was 10.00 years. The median (range) subjective myopia of the right eye at baseline was 6.41D (5.00–8.00D) and 6.22D (6.00–8.00D) for PR ortho-k and spectacle groups, respectively (p > 0.05). Nineteen (79%) PR ortho-k subjects achieved successful lens fit at the one month visit and the median myopic reduction was 3.75D in the right eye. The incidence of (mild) corneal staining in PR ortho-k subjects reduced from 30% at the first overnight lens wear to 16% at the 1-month visit. Corneal pigmented arc was observed in 32% of PR ortho-k subjects at the 1-month visit.ConclusionsPR ortho-k was successfully applied to high myopic children with no significant changes in ocular health/best corrected visual acuity after one month of lens wear.     

Performance and predictability of a new large diameter contact lens design in keratoconic corneae

ObjectivesTo evaluate the clinical performance and predictability using corneal topography in the fitting of a new large-diameter rigid gas permeable (RGP) contact lens design in eyes with keratoconus (KCN).MethodsThis study presents a review of eyes fitted with Alexa ES lenses for nonsurgical optimisation of visual correction. Anterior steep simulated keratometry (sim-K steep), corneal diameter (HVID), the Curvature at the apex in diopters (Cc), and distance from the corneal apex to the centre of the cornea (Lc) in millimetres derived from the Cone Location and Magnitude Index (CLMI) were recorded. Visual acuity, mean wearing time, final sagittal depth and adverse events were also recorded. Correlations between topographic indices and base curve were evaluated using the Pearson correlation coefficient.ResultsForty-six eyes from 26 patients (19 males/ 7 females) were included. Mean visual acuity improved from 0.49 ± 0.32 with glasses, to -0.02 ± 0.10 with the contact lens. The mean daily wear time was 12.19 ± 1.96 hours. No complications were detected in 95.65% of the eyes [95% CI (83.9%-99.2%)] but two episodes of non-infectious keratitis. The average sagittal depth of the lenses fitted was 0.425 ± 0.15 mm, and it was positively correlated with the Cc value (r² = 0.66, p< 0.0001, n=46) derived from the CLMI index of the pre-fitting topography.ConclusionsCorneoscleral RGP contact lenses are a safe, and effective alternative for managing KCN patients to corneal lenses. Also, clinical data derived from the corneal topography could be used to help to decide the first diagnostic lens to be assessed, easing the overall fitting process.     

Corneoscleral junction angle in healthy eyes assessed objectively

PurposeTo introduce a fully objective method to measure corneoscleral junction (CSJ) angle and evaluate the CSJ angle in healthy eyes.MethodsCorneoscleral topography (Eye Surface Profiler, ESP) was acquired from the right eye of 105 healthy Caucasian subjects, ranging from 18 to 59 years old. From the raw anterior eye height data, the topographic limbus was automatically demarcated in 360 semi-meridians. Further, in limbal location, the CSJ angle was automatically calculated from corneoscleral height data using neighbouring auxiliary points for angle calculation. Additionally, CSJ angle was statistically analysed regionally.ResultsThe mean CSJ angle was 177.5 ± 1.1°. There is a mean difference of 7.7 ± 3.7° between the steepest (smallest) and flattest (largest) CSJ angle within the same eye. There exist statistically significant differences between temporal (178.2 ± 1.4°) and nasal (176.4 ± 1.1°) regions (paired t-test, p < 0.001), and between superior (178.1 ± 1.1°) and inferior (177.9 ± 1.1°) regions (p = 0.038). CSJ angle is correlated with limbus position (r = 0.43, p < 0.001).ConclusionCSJ angle is rotationally asymmetric. CSJ varies regionally, being the smallest (steepest) in the nasal region. Significant rough changes in CSJ angle were observed for some healthy individuals.