Corneal topography for pancorneal toric edge rigid gas-permeable contact lens fitting in patients with keratoconus,and differences in age and gender

PurposeTo determine whether pancorneal rigid gas-permeable toric edge contact lenses (pancorneal RGP-CL) fitting could be improved by using non-central corneal shape predictors, and to compare these parameters with respect to age and gender in patients with keratoconus.MethodsThe current study was a retrospective study including patients with clinically evident keratoconus (on videokeratography) from three medical centres located in the Netherlands. Medical history, visual acuity, refraction, and contact lens characteristics were documented. All participants underwent ophthalmic examination including measurement of K-values (steepest, flattest, mean, as a non-central parameter the minimum radius [K-minimum], and all combined) using corneal topography. Fitting of contact lenses was based on the fluorescence pattern as seen during slitlamp examination.ResultsA total of 378 eyes of 218 patients with keratoconus were included. Of these, 257 (68%) were fitted with a pancorneal RGP-CL. The central K-values, K-steep and K-flat, performed well in predicting the base curve radius, though, for pancorneal RGP-CL the non-central K-minimum added most (35.5%) to the total explained variance in base curve radius. Regarding age and gender, women tended to have larger K-values than men. No differences in K-values were found with respect to age.DiscussionWe found that including the K-minimum as a non-central parameter may improve prediction of the best base curve radius for pancorneal RGP-CL and may reduce the number of trial contact lenses. In line with other studies, suggestive evidence was found for a difference in pattern of progression of keratoconus with gender, but not with age.     

Assessment of corneal endothelial cell density in patients with keratoconus not using contact lenses

PurposeTo assess the corneal endothelial cell density (ECD) in keratoconus patients with no history of contact lens use.SettingYuzuncu Yil University, School of Medicine and Van Training and Research Hospital, Department of Ophthalmology, Van, Turkey.DesignCross-sectional controlled study.MethodsThe eyes of 65 patients with the diagnosis of keratoconus with no history of contact lens wear and the eyes of 40 healthy controls were prospectively examined using the Heidelberg Retinal Tomography Rostock Cornea Module (HRT3/RCM). The average ECD from the two groups were then compared.ResultsOf the cases with keratoconus, 44 (67.7%) were men and 21 (32.3%) were women. The mean age was 20.9 ± 6.8 (range = 10–41) years. Of the controls, 28 (70%) were men and 12 (30%) were women. The mean age was 23.9 ± 5.8 (range = 14–35) years. Of the 65 eyes with keratoconus, 19 (29.2%) had mild keratoconus, 21 (32.3%) had moderate keratoconus, and 25 (38.5%) had severe keratoconus. The mean ECD was 2731.6 ± 303.2 cells/mm² in cases with keratoconus and 2664.9 ± 319.5 cells/mm² in controls. There was no difference between the densities (unpaired t-test, P = 0.4). No significant relationships were found between the ECD data and central corneal thickness or steepest keratometric.ConclusionsEndothelial cell density was unaltered in keratoconic patients without a history of contact lens use when compared with healthy controls. Change in ECD is independent from the central corneal thickness and the stage of keratoconus.     

Measure of keratoconus progression in patients with vernal keratoconjunctivitis using scanning slit topography

PurposeTo document topographic changes using Orbscan in patients with keratoconus and vernal keratoconjunctivitis over 1 year.Material and methodsRetrospective analysis of clinical and Orbscan data of 22 eyes of 11 patients with keratoconus and VKC with follow up over 1 year period was done. The parameters studied included patients demographics, clinical features, visual acuity, refraction and Orbscan IIz. The changes in various Orbscan parameters were studied over the 1-year period.ResultsMean age was 14 ± 4.1years. 20 eyes had clinical keratoconus, while 2 had forme fruste keratoconus. 8 eyes of 22 showed evident progression (>1 diopter change in mean simulated (sim) K over 12 months). There was no significant difference in the visual acuity or clinical features over follow up. In patients with progression, statistically significant change (p < 0.05) was found in posterior float curvature, sim K astigmatism and maximum astigmatism. Rest of the parameters did not show significant change. Among the patients without evident progression, none of the parameters showed significant change. On comparing the patients with clinical signs of keratoconus with those with only topographic signs of keratoconus, there was no difference between the two groups with respect to the rate of progression of keratoconus. Patients with both mixed type and pure palpebral type of VKC had comparable Orbscan parameters at baseline and 1 year follow up and similar progression rate of keratoconus.ConclusionSerial topographic analysis provides numerical information about various corneal parameters in patients with vernal keratoconjunctivitis and keratoconus.     

Anterior segment characteristics of keratoconus eyes in a sample of Asian population

PurposeTo assess changes in anterior segment parameters of keratoconus eyes at different stages of the disease in a sample of the Asian population.MethodsFiles of 32 patients (48 eyes) diagnosed as clinical keratoconus were assessed and the following parameters noted: central corneal thickness (CCT), thinnest corneal thickness (TCT), location of thinnest pachymetry, anterior chamber depth (ACD) at the centre from posterior corneal surface, ACD at 1, 2 and 3 mm inferior-paracentral, ACD at thinnest pachymetry, anterior chamber volume (ACV) and anterior chamber angle (ACA). For analysis, keratoconus eyes were classified into 3 subgroups according to mean keratometry readings (mild: K ≤ 47.0 D, moderate: 47.0 < K < 52.0 D, and severe: K ≥ 52.0 D). Forty-five subjects (45 right eyes) were recruited as a control group. They underwent Pentacam tomographic evaluation. The same parameters were recorded for control subjects as in the keratoconus patients.ResultsEach keratoconus subgroup comprised of 16 eyes. CCT, TCT, ACD at centre, ACD at 1, 2 mm inferior-paracentral and ACD at thinnest pachymetry were statistically different between mild and severe keratoconus groups (P < 0.05). There were also significant differences between normal with each of the moderate and severe keratoconus groups (P < 0.05). Non-significant differences were found in ACV (P = 0.84) and ACA (P = 0.71) between all measured groups.ConclusionWith the exception of ACV and ACA, parameters that include CCT, TCT, ACD at centre, thinnest pachymetry and 1, 2 mm inferior-paracentral were significantly altered with progression of keratoconus. These findings may be useful in monitoring and management of keratoconus patients.     

Trans epithelial corneal collagen crosslinking for progressive keratoconus: 6 months follow up

PurposeTo evaluate keratoconus biomechanical changes after transepithelial corneal collagen cross linking (TE CXL) using riboflavin and ultraviolet A (UVA).SettingSecond University of Naples, Naples, Italy.DesignProspective non comparative case series study.MethodsPatients with progressive keratoconus were examined, before and during a 6 months follow up after TE CXL, with a Pentacam, an Ocular Response Analyzer and an IOLMaster.Best corrected visual acuity (BCVA), refraction, corneal thinnest point (CTP), keratometry readings at the keratoconus apex (K_max), axial eye length (AL), corneal volume (CV) anterior chamber volume (ACV), anterior chamber depth (ACD), corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated.ResultsThirty-six eyes of 36 patients with progressive keratoconus were analyzed. Six months after treatment there was a significant improvement in BCVA (p < 0.01), no significant changes in refraction (p = 0.57), CTP (p = 0.07), K_max (p = 0.88), AL (p = 0.07), CV (p = 0.38), ACV (p = 0.07), ACD (p = 0.7), CH (p = 0.1) and CRF (p = 0.3).ConclusionsAccording to our results TE CXL stabilizes most of the patients with progressive keratoconus, without affecting in negative way the corneal elasticity.     

Kerasoft IC compared to Rose-K in the management of corneal ectasias

PurposeTo determine the efficacy of the KeraSoft^® IC (KIC) (Ultravision International Limited, Bedfordshire, UK), a silicone hydrogel contact lens, for the optical management of non-surgical corneal ectasias and to compare it with the Rose-K 2 RGP contact lens.MethodsIn a retrospective study ninety-four eyes fitted with KIC (group A) were compared with seventy-seven eyes fitted with Rose-K^® RGP lenses as a control group. Ocular diagnoses, corneal curvature by topography, refraction, best spectacle-corrected visual acuity (BSCVA), and age at time of fitting were noted. Outcome data included average daily wearing time, contact lens complications, visual acuity with the lens (BCLCVA), power of the lenses and length of follow-up.ResultsDifferences in either BCLCVA or wearing time could not be statistically established (p = 0.63, p = 0.15) between both groups. More biomicroscopic complications were found in the RGP group, basically corneal staining (P < 0.0001). In the KIC group, BCLCVA was statistically similar between types of ectasia (p = 0.19) as well as in mild and moderate keratoconus (p = 0.45).ConclusionsKIC is a good alternative for the optical management of irregular corneal astigmatism in non surgical corneal ectasias such as keratoconus and pellucid marginal degeneration.     

Efficacy of corneal tomography parameters and biomechanical characteristic in keratoconus detection

AimTo determine the efficacy of corneal thickness parameters and corneal biomechanical properties (CBPs) in discriminating between normal and keratoconus eyes.MethodAfter performing a comprehensive ophthalmic examination, 50 mild to moderate keratoconus and 50 age and sex matched myopic astigmatism eyes were prospectively included in the study. The corneal topographic maps and CBP were obtained by Pentacam and Ocular response analyser, respectively. Central corneal thickness (CCT), thinnest corneal thickness (TCT), corneal thickness (CT) and percentage thickness increase (PTI) at 1, 3 and 5 mm from the thinnest point and corneal volume (CV) at 3, 5, 7 and 10 centred on thinnest point, corneal hysteresis (CH) and corneal resistance factor (CRF) were recorded. Independent t-test and receiver operating characteristic (ROC) were done with SPSS software (version 15.0, SPSS, Inc.).ResultsCCT, TCT, CT at 1, 3 and 5, CV at 3, 5, 7 and 10 mm, CH and CRF were significantly lower in keratoconus eyes compared to controls (p < 0.001). In addition, PTI at 1, 3 and 5 mm from the thinnest point showed significantly higher values in keratoconus group. ROC analysis demonstrated good predictive accuracy for cut-off point values. However, the centrally located indices had higher predictive accuracy compared to the peripherally located indices.ConclusionAlthough good sensitivity and specificity were found for the mentioned parameters, the centrally located indices had higher predictive accuracy compared to peripherally located indices. It is suggested to use a combination of corneal pachymetry together with CBP for more accurate detection of keratoconus.     

Evaluation of central corneal thickness after cataract surgery,penetrating keratoplasty and long-term soft contact lens wear

PurposeThe aim of this study was to compare central corneal thickness (CCT) between corneas of normal healthy eyes (cNHE), corneas of eyes that had undergone cataract surgery by clear corneal phacoemulsification with implantation of an intracapsular intraocular lens (cIOL), corneal grafts after penetrating keratoplasty (gPK) and corneas of long-term soft contact lens wearers (cCL).MethodsThe study design was a consecutive cross-sectional trial. CCT was measured using rotating Scheimpflug camera (Pentacam, software version 1.16r04) in 80 cNHE, 79 cIOL, 46 gPK and 78 cCL. Analysis of variance (one-way ANOVA) was performed to compare differences of mean values between these four groups. Pearson's or Spearman's correlation coefficient (r) was determined between CCT value and age, follow up time after penetrating keratoplasty (timePK) or contact lens wearing time (timeCL).ResultsMeans of CCT measurements were comparable between cNHE (mean CCT ± standard deviation, 554 ± 36 μm), cIOL (551 ± 40 μm) and gPK (534 ± 52 μm) as determined by one-way ANOVA. Mean CCT values in cCL (537 ± 37 μm) were statistically significantly lower in comparison to cNHE (p = 0.026, 95% CI = 1.43–31.44). There was no linear correlation between age and CCT values of cNHE and cIOL (p = 0.841, r = −0.031 and p = 0.931, r = 0.011, respectively). No linear relationship was determined between CCT values of cCL and timeCL (p = 0.315, r = −0.125). CCT values of gPK did not correlate with timePK (p = 0.738, r = 0.054).ConclusionsThe data reported here indicate that in the same statistical model among CCT values of cNHE, cIOL and gPK only long-term soft contact lenses (CL) wearer have significantly lower CCT measurements.     

Which soft contact lens power is better for piggyback fitting in keratoconus?

PurposeTo evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus.MethodsNineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of −3.00, −1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated.ResultsNegative- and plano-powered soft lenses flattened (p < 0.05 in all cases), whereas positive-powered lenses did not induce any significant changes (p > 0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (p < 0.05 in both cases) and increased with +3.00 D lenses (p = 0.03) in comparison to the naked eye. No statistically significant differences were found in MFE with any soft lens power in comparison to the naked eye (p > 0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p < 0.05 in all cases). No statistically differences were found in HOA RMS and spherical-like aberration (both p > 0.05). Statistically differences were found in coma-like and secondary astigmatism (both p < 0.05).ConclusionNegative-powered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting.     

RGP contact lens fitting in keratoconus using FITSCAN technology

PurposeTo assess and compare the base curve (BC) of rigid gas permeable contact lens (RGP) that were calculated by FITSCAN using corneal topography (Orbscan IIz) and the diagnostic contact lens fitting method in keratoconus eyes.Materials and methodsA prospective comparative study of 85 keratoconus eyes was conducted. Two masked observers calculated the contact lens parameters of RGP lens by diagnostic fitting method and using FITSCAN technology. The base curves calculated by two methods were compared using Wilcoxon signed rank test and agreement between two methods were analysed using Bland–Altman plot.ResultsEighty-five eyes from 55 keratoconus patients were included in the study. The mean age was 17.63 ± 2.78 (range: 12–23) years and among them 46 were males. The keratoconus was graded into mild, moderate and severe based on average keratometry values. The base curve calculated by the FITSCAN is on average 0.22 mm higher than that calculated by diagnostic method (P value <0.0001, 95% CI = 0.155, 0.245, Wilcoxon signed rank test) and the bias between the two methods was found to be 2.7% (Bland–Altman plot), indicating systematic bias between the two modalities. By single linear regression analysis, the base curve of RGP contact lens could calculated by using the formula, base curve (BC) = (FITSCAN calculated BC × 0.86563) + 0.78738.ConclusionOur study showed that selecting the BC of the initial trial lens 0.22 mm steeper than the FITSCAN calculated base curve, may help to reduce the complexity of RGP contact lens fitting in keratoconus.     

Predicting success with silicone-hydrogel contact lenses in new wearers

Purposeto evaluate changes in tear metrics and ocular signs induced by six months of silicone-hydrogel contact lens wear and the difference in baseline characteristics between those who successfully continued in contact lens wear compared to those that did not.MethodsNon-invasive Keratograph, Tearscope and fluorescein tear break-up times (TBUTs), tear meniscus height, bulbar and limbal hyperaemia, lid-parallel conjunctival folds (LIPCOF), phenol red thread, fluorescein and lissamine-green staining, and lid wiper epitheliopathy were measured on 60 new contact lens wearers fitted with monthly silicone-hydrogels (average age 36 ± 14 years, 40 females). Symptoms were evaluated by the Ocular Surface Disease Index (OSDI). After six months full time contact lens wear the above metrics were re-measured on those patients still in contact lens wear (n = 33). The initial measurements were also compared between the group still wearing lenses after six months and those who had ceased lens wear (n = 27).ResultsThere were significant changes in tear meniscus height (p = 0.031), bulbar hyperaemia (p = 0.011), fluorescein TBUT (p = 0.027), corneal (p = 0.007) and conjunctival (p = 0.009) staining, LIPCOF (p = 0.011) and lid wiper epitheliopathy (p = 0.002) after six months of silicone-hydrogel wear. Successful wearers had a higher non-invasive (17.0 ± 8.2 s vs 12.0 ± 5.6 s; p = 0.001) and fluorescein (10.7 ± 6.4 s vs 7.5 ± 4.7 s; p = 0.001) TBUT than drop-outs, although OSDI (cut-off 4.2) was also a strong predictor of success.ConclusionSilicone-hydrogel lenses induced significant changes in the tear film and ocular surface as well as lid margin staining. Wettability of the ocular surface is the main factor affecting contact lens drop-out.     

Conjunctival UV autofluorescence – Prevalence and risk factors

PurposeAutofluorescence of ultraviolet (UV) light has been shown to occur in localised areas of the bulbar conjunctiva, which map to active cellular changes due to UV and environmental exposure. This study examined the presence of conjunctival UV autofluorescence in eye care practitioners (ECPs) across Europe and the Middle East and its associated risk factors.MethodImages were captured of 307 ECPs right eyes in the Czech Republic, Germany, Greece, Kuwait, Netherlands, Sweden, Switzerland, United Arab Emirates and the United Kingdom using a Nikon D100 camera and dual flash units through UV filters. UV autofluorescence was outlined using ImageJ software and the nasal and temporal area quantified. Subjects were required to complete a questionnaire on their demographics and lifestyle including general exposure to UV and refractive correction.ResultsAverage age of the subjects was 38.5 ± 12.2 years (range 19–68) and 39.7% were male. Sixty-two percent of eyes had some conjunctival damage as indicated by UV autofluorescence. The average area of damage was higher (p = 0.005) nasally (2.95 ± 4.52 mm²) than temporally (2.19 ± 4.17 mm²). The area of UV damage was not related to age (r = 0.03, p = 0.674), gender (p = 0.194), self-reported sun exposure lifestyle (p > 0.05), geographical location (p = 0174), sunglasses use (p > 0.05) or UV-blocking contact lens use (p > 0.05), although it was higher in those wearing contact lenses with minimal UV-blocking and no spectacles (p = 0.015). The area of UV damage was also less nasally in those who wore contact lenses and spectacles compared to those with no refractive correction use (p = 0.011 nasal; p = 0.958 temporal).ConclusionUV conjunctival damage is common even in Europe, Kuwait and UAE, and among ECPs. The area of damage appears to be linked with the use of refractive correction, with greater damage nasally than temporally which may be explained by the peripheral light focusing effect.     

Comparison of normal and keratoconic corneas by Galilei Dual-Scheimpflug Analyzer

Background and objectiveTo determine the efficacy of different Galilei Scheimpflug-Analyzer (GSA) parameters in discriminating between keratoconic and myopic eyes.Patients and methodsGSA measurements were obtained for 67 patients (67 eyes) with keratoconus and 151 patients (151 eyes) with myopia or myopic astigmatism. Several parameters, provided by the software or derived from the elevation maps, were evaluated and compared for the two groups.ResultsBetween the two groups, statistically significant differences were observed for all corneal parameters obtained by GSA (P < 0.001) except for the anterior chamber depth (P = 0.149). ROC analysis determined that posterior corneal elevation was the best predictive parameter (area under the curve: 0.99). The posterior corneal elevation, at a cut-off value of 18.5 μm, had 98.5% sensitivity and 98.3% specificity in discriminating keratoconus from myopic eyes.ConclusionElevation, pachymetric and keratometric parameters measured by the GSA, as well as the specific predictive GSA software parameters can effectively distinguish advanced keratoconus from myopic corneas. Also, keratoconus that is easily diagnosed by other means can be diagnosed easily by GSA software parameters.     

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.     

Patient ocular conditions and clinical outcomes using a PROSE scleral device

PurposeTo determine the type and distribution of ocular conditions cared for in a clinic dedicated to scleral devices and to report the clinical outcomes afforded by this approach.MethodsFifty-one charts of patients fitted unilaterally or bilaterally with a scleral device (Prosthetic Replacement of the Ocular Surface Ecosystem – PROSE) in a two year period were retrospectively reviewed. Patient demographics, ocular diagnoses, associated systemic conditions, best corrected visual acuity (BCVA) before and after fitting, Visual Function Questionnaire score (VFQ-25), and ocular surface disease index (OSDI) score were collected.ResultsAll 51 patients were successfully wearing the PROSE device for a period of anywhere from weeks to years. The most common reasons for fitting were to relieve symptoms of moderate to severe dry eye syndrome (“DES”, n = 25), management of refractive problems (“refractive”, n = 23) with keratoconus being the most common (n = 14), and to manage other anomalies (“other”, n = 3). Best corrected visual acuity (logMAR) improved with the wearing of the PROSE device for both the DES (17 letters) and the refractive group (10 letters), but not the “other” group. No serious complications were recorded for any of the patients.ConclusionsThe PROSE device is a useful option not only for the management of ocular surface disease and optical imperfections, but also for other ophthalmic conditions. Moderate to severe dry eye was the most common anomaly managed, followed by eyes with irregular corneal astigmatism. DES and refractive patients experienced improvement in visual acuity with wearing of the PROSE device.     

Efficacy of spherical aberration correction based on contact lens power

PurposeTo investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses).MethodsOcular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch + Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (−7.00 diopters (D), −5.00 D, −3.00 D, −1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone.ResultsFor the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from −0.15 to −0.05 μm, for all lens powers except for the −1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at −7.00 D (p = 0.040), −3.00 D (p = 0.015), −1.00 D (p < 0.001), +1.00 D (p = 0.006), and +3.00 D (p < 0.001) powers.ConclusionAn aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of −0.15 to −0.05 μm over a 6 mm aperture.     

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.     

Long-term outcomes of intrastromal corneal ring segment implantation for post-LASIK ectasia

PurposeTo report the long-term results of intrastromal corneal ring segments (ICRS) for postoperative LASIK ectasia.MethodIn this retrospective interventional cases series, 8 eyes of 6 patients who underwent femtosecond laser-assisted ICRS implantation for post-LASIK ectasia were enrolled. Main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent refraction, and average keratometry (K_avg) values were assessed.ResultsMean ± SD follow-up was 67 ± 21 months (range, 36–96 months). The mean UDVA, CDVA, spherical equivalent refraction, and K_avg values were significantly improved at all postoperative visits when compared to baseline values. No serious complications were observed during follow-up.ConclusionOur long-term findings showed that ICRS yielded improvements in visual acuity, refractive status, and keratometric values without any progression in cases with post-LASIK corneal ectasia.     

Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: A prospective fellow eye study

PurposeTo compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK).SettingBeyoğlu Eye Training and Research Hospital.DesignProspective comparative case series.MethodsSixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10 diopters (D) and a difference ≤0.50 D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months).ResultsPreoperative SE was similar in both groups (p = 0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p < 0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95 ± 1.47 and 9.02 ± 1.27, respectively (p = 0.852), and the mean CRF values were 7.77 ± 1.37 and 8.07 ± 1.26, respectively (p = 0.380).ConclusionCH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values.     

Changes in tear film,corneal topography,and refractive status in premenopausal women during menstrual cycle

PurposeTo investigate the changes in a questionnaire based subjective symptomatology, tear film break-up time, tear volume, corneal topography, and refractive status in premenopausal women during menstrual cycle.MethodsSeventeen premenopausal females and 15 healthy males were enrolled in this prospective study. After routine ophthalmologic examination, an ocular surface disease index questionnaire was administered, tear film break-up time (TBUT), and Schirmer I tests were performed. Keratometry readings and refractive status were also obtained. All examinations were repeated at day 21, day 12 and day 2.ResultsOSDI score in day 21 was significantly lower than that in day 12 (p = 0.004) and day 2 (p = 0.01) in the female patients; however, no significant change was found in the male subjects (p > 0.05). No statistically significant difference was found in TBUT and Schirmer I tests, keratometry, and refraction results in both of the female and male subjects at all of the test points (p > 0.05). There was a significant correlation between OSDI score and TBUT (p = 0.02, p = 0.03, respectively), and Schirmer I test at day 12 (p = 0.004, p = 0.008, respectively). A significant negative correlation was found between oestrogen level and horizontal keratometry values at day 21 (r = −0.5, p = 0.03; r = −0.4, p = 0.04, respectively) for the right and left eyes in the female subjects.ConclusionOur study confirms that fluctuations in the blood levels of oestrogen produce alterations in ocular surface equilibrium during the menstrual cycle and consequently affect the subjective dry eye symptoms in female patients. However, no ocular surface parameter changes were observed.