Ten years of disposable contact lenses - a review of benefits and risks

The performance and benefits as well as the risks and complications of disposable soft lenses (single use disposable or re-used 2-4 weeks) are reviewed in relation to corneal physiology. Modern designs and advanced technology have resulted in disposable lenses providing excellent visual performance. Fewer subjective symptoms (e.g. dryness and grittiness), slit-lamp findings (such as injection and tarsal abnormalities), and inflammatory responses (papillary conjunctivitis; contact lens-induced acute red eye) have been reported with disposable lenses than with conventional soft lenses. The risk of contact lens-induced keratitis (CLIK) has been reported to be higher for daily wear of disposable lenses than for other lens types by UK investigators. Other studies have shown the risk of CLIK with disposable lenses to be equal to that with conventional soft lenses, and in two extensive Swedish studies, the incidence of severe keratitis was found to be significantly lower for daily wear (DW) of disposable lenses than for DW of conventional soft and rigid gas permeable lenses. Both the total complication rate and the number of unscheduled visits are found to be significantly lower for disposable lenses than for conventional soft lenses in several studies. Comfort has been reported to be significantly better and overall satisfaction significantly greater with disposable lenses than with conventional soft lenses according to many studies. These may be important reasons why the success rate for disposable lens wear is reported to be fairly high, generally 70-90%. The importance of appropriate care for 're-usable disposable lenses' must be stressed. One day disposable lenses, if used as directed, will eliminate the risk factors of inadequate cleaning and disinfection as well as contaminated lens cases.     

Feasibility of contact lens fitting on keratoconus patients with INTACS inserts.

PURPOSE: To demonstrate the feasibility of contact lens fitting in keratoconus patients with INTACS inserts. METHODS: A chart review was conducted of all patients with bilateral keratoconus who were treated with INTACS inserts on one eye and who were subsequently referred for contact lens fitting in a university based contact lens practice between April 2000 and April 2002. The study was a retrospective, non-comparative case series. The uncorrected and best spectacle corrected visual acuity (BSCVA) after INTACS implantation surgery, postoperative best contact lens-corrected visual acuity (BCLVA), number of diagnostic contact lenses used, number of contact lenses ordered within a 4-month follow-up period, contact lens complications encountered, final base curves, final lens powers, and final wearing times were determined. RESULTS: Three keratoconic patients meeting the selection criteria were found through the chart review. Prior to surgery, all patients had uncorrected visual acuity (UCVA) of 2.0 logMAR (counting fingers). This improved to a mean of 0.81+/-0.25 logMAR (20/125-1) after surgery. Mean BSCVA also improved from 0.51+/-0.30 logMAR (20/60-2) to 0.30+/-0.16 logMAR (20/40). The mean postoperative best contact lens-corrected visual acuity was 0.02+/-0.10 logMAR (20/20-1). The number of diagnostic lenses ranged from 1 to 7. The numbers of contact lenses ordered during the 4-month follow up period ranged from 1 to 3. Two eyes were fitted with larger than usual lens designs made of rigid gas-permeable material and one eye was fitted with a toric soft lens. The final lens power ranged from +1.25 to -21.0D with a mean spherical equivalent of -7.46+/-11.89 D. Final wearing times ranged from 2.5 to 12.0h. CONCLUSION: Fitting contact lenses on keratoconus patients who have INTACS inserts is feasible and has a role in augmenting their vision.     

Diagnostic patterns in keratoconus

PurposeTo investigate the current patterns of diagnosis and referral in keratoconus.MethodsA retrospective chart review was performed of patients who had recently been diagnosed with keratoconus and attended dedicated clinics at Antwerp University Hospital, Belgium and Maria Middelares General Hospital, Ghent, Belgium between June 2013 and February 2018. Exclusion criteria included longstanding keratoconus diagnosis, reduced cognitive capabilities and prior surgical procedures (corneal crosslinking, penetrating keratoplasty or any type of refractive surgery).ResultsThree-hundred and ninety-nine patients (722 eyes) were included in this study. The mean age was 24.7 ± 6.5 years and the average maximal keratometry was 51 ± 5.2 D for the better eye and 58.4 ± 9.6 D for the worse eye. Upon diagnosis, 233 eyes (32.2 %) and 51 eyes (7.1 %) had a thinnest pachymetry <450 and <400 μm, respectively. At 6-month follow-up, 58 % of patients had been fitted with specialty contact lenses. During follow-up, 199 eyes (27.6 %) underwent corneal crosslinking. One patient underwent corneal graft surgery of his worse eye due to contact lens intolerance and insufficient visual acuity.ConclusionDespite advances in diagnostic tools, keratoconus is often diagnosed at a relatively late stage. Earlier detection of keratoconus would increase the overall clinical benefit of corneal crosslinking. Further research into screening strategies is required to develop cost-effective screening programs.     

Contact lens care in keratoconus.

PURPOSE: To quantify the complexity involved in fitting contact lenses on the eyes of patients with keratoconus. METHODS: The contact lens care of one randomly selected eye each of 38 keratoconus patients was retrospectively analyzed and compared to that of 38 gender and age matched controls. We evaluated the number of diagnostic contact lenses used to establish the initial contact lens order, number of ordered rigid gas permeable (RGP) contact lenses needed to complete the fit, number of office visits during the initial 4 months of care, best spectacle and RGP contact lenses corrected Log MAR visual acuities, complications encountered, and whether or not the patient was successful in contact lens wear. RESULTS: Keratoconic eyes statistically used more diagnostic lenses, more ordered lenses, and more office visits than did normal eyes. Visual acuities improved from an average of 20/40 with spectacles to an average of 20/20 by use of RGP contact lenses in keratoconic eyes. Visions were corrected to 20/20 with both spectacles and contact lenses in control eyes. Sixty nine percent (69%) of keratoconic eyes and 95% of controls were successful in contact lens wear. CONCLUSIONS: Contact lens care of keratoconic eyes is more challenging than care of normal eyes because of the need for more diagnostic and ordered contact lenses and the use of more professional time. Keratoconic eyes may suffer more complications than normals during contact lens care, but this does not affect the success rates, and such patients benefit from enhanced visual acuity with RGP contact lenses compared to that achieved with spectacles.     

Contact lens prescribing trends in the UK hospital eye service

PurposeThe aim of this study was to evaluate the types of contact lenses fitted by hospital optometrists within the Midlands region of the United Kingdom (UK).MethodA questionnaire was sent to all the lead optometrists of the Midlands Hospital Optometry Group (MHOG). This group includes optometry hospital eye departments within the Midlands region of the UK. The questionnaire requested information of their last ten contact lens fitting appointments. Details of the patient’s age, gender, lens type, wearing times, and presenting condition were retrospectively taken from the patients’ records using the appointment diary to identify the last ten patients fitted with contact lenses.ResultsDetails from a total of 109 contact lens fits were collected. This included 45 females and 64 males with a mean age of 39.4 ± 17.4 years. The mean wearing time was 6.3 ± 1.0 days per week and 10.7 ± 5.1 h per day. Sixty-one percent of the contact lenses fitted were for patients with keratoconus and over half of all the contact lenses fitted were corneal rigid gas permeable lenses.ConclusionThis study highlighted that the main reason for fitting contact lenses in hospital contact lens practice is primary corneal ectasia, and mainly keratoconus. Whilst most patients with keratoconus were fitted with corneal rigid gas permeable contact lenses, around 1 in 6 were fitted with soft contact lenses. This study addresses a gap in the literature about contact lenses fitted in UK hospitals and how they differ from community contact lens practice.     

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.     

Scleral contact lenses for visual rehabilitation after penetrating keratoplasty: Long term outcomes

PurposeTo evaluate the success rate of highly gas permeable scleral contact lenses (SCL) for visual rehabilitation after penetrating keratoplasty (PK), over a period of up to 9 years.MethodsA total database of 31 consecutive patient fitted with SCL between January 2004 and December 2009 was retrospectively reviewed. Demographic data, etiology prior to lens fitting, visual outcomes, follow up time and complications were analyzed.ResultsAll eyes were fitted due to inadequate spectacle-corrected vision after successful penetrating keratoplasty or failure of other contact lens modalities. Out of 31 patients fitted, 28 (33 eyes) continue to wear SCL for periods between 0.5 and 8.8 years. The mean duration of follow-up after contact lens fitting was 5.2 ± 2.2 years. The mean age of corneal graft was 17.6 ± 11.4 years (range 4.3–42), and the mean interval between PK and initial contact lens fitting was 12.2 ± 10.7 years (range 0.7–36.0). The average steepest keratometry of our cohort was 55.0 ± 7.5 diopter (D) and the refractive astigmatism was 8.0 ± 4.4 D. The mean contact lens corrected visual acuity (BCVAcl) was 0.78 ± 0.25 (range 0.3–1.2). Twenty-three (82%) patients achieved a functional vision of 0.5 or more.During the studied period, ten (30.0%) eyes presented at least one graft rejection episode and two eyes (6%) had an episode of microbial keratitis. Corneal transplants of 20 years or more show a higher rate of refits due to ectasia recurrence.ConclusionsScleral lenses should be considered as lens of choice in eyes with complex corneal geometry, as besides visual rehabilitation, their use may delay or prevent further surgical involvement.     

A new rigid gas-permeable semi-scleral contact lens for treatment of corneal surface disorders.

Some extreme corneal irregularities cannot be treated adequately with corneal contact lenses. For such cases a rigid semi-scleral lens can be prescribed. We evaluated the use of a highly gas permeable rigid semi scleral lens in patients with diseased corneas for whom conventional contact lens strategies had failed. Twenty two patients (29 eyes) were successfully fitted with individually manufactured semiscleral lenses. Corneal hypoxia, which has previously limited the use of polymethylmethacrylate (PMMA) scleral contact lenses, did not occur. The semi scleral lenses were well tolerated. Two cases were selected to illustrate the fitting of these lenses.     

Randomised controlled trial of corneal vs. scleral rigid gas permeable contact lenses for keratoconus and other ectatic corneal disorders

PurposeTo compare the comfort and visual performance of corneal rigid gas permeable contact lenses (CoL) and scleral rigid gas permeable contact lenses (SL) in participants with corneal ectasia, successfully wearing “habitual” CoL.MethodsIn a randomised controlled trial (RCT) with a 2 × 2 crossover, 34 participants were recruited and randomised into two groups. Group 1 (sequence AB), were fitted in period 1, with new CoL and after a 4-week washout period, in which habitual CoL were worn, were fitted with and crossed-over to SL, period 2. Group 2 (sequence BA), were first fitted with SL in period 1 and after a washout period of 4 weeks, crossed-over to new CoL, period 2. The median lengths in weeks of Periods 1 and 2 were: 17.5 (IQR 12.4) and 14.5 (IQR 6.2) respectively. The outcome measures for visual performance were best corrected visual acuity and the contrast sensitivity function. Vision related quality of life (Qol) was assessed using the National Eye Institute Visual Function Questioannaire-25 and reported subjective perception of vision (SPV) and reported subjective perception of comfort (SPC) scores, recorded on a scale from 1–10. The final outcome measure was the selection of the preferred lens type at the completion of the RCT.ResultsFor the 30 who completed the trial, significantly higher SPC scores were found for SL compared to CoL (p = 0.002). Significantly higher SPC scores for CoL were found in participants who selected CoL as their preferred lens for future use, compared to those who selected SL (p = 0.009). All other outcomes exhibited no significant difference between the experimental lenses. There was no significant difference (p=0.86) in the proportion preferring CoL (53%) and SL (47%).ConclusionSignificantly better comfort was reported for SL compared with CoL. Significantly higher comfort in CoL was found in those who preferred CoL, than those who preferred SL. Successful CoL wearers whose SPC in CoL is <7 are likely to achieve better comfort with SL. On average, successful CoL wearers found SL more comfortable and there are unlikely to be any significant visual or visual Qol advantage or disadvantage in refitting successful CoL wearers with keratoconus and other corneal ectasia disorders, with SL and vice versa.     

A novel collaboration: Multifocal RGPs and low vision aids increase quality of life in visually impaired

ObjectivesBy presenting 2 cases, this study aimed to discuss the utility of multifocal rigid gas permeable contact lenses in the low vision patient population, and their ability to decrease reliance on low vision aids and to increase quality of life.MethodsA retrospective case series of 2 patients receiving care from two specialty practice locations was performed. Both patients were visually impaired presbyopic myopes, and sought care from both contact lens and low vision specialties in order to improve visual function and enhance their ability to perform activities of daily living. They were each fit with multifocal gas permeable contact lenses to be used in conjunction with low vision devices. The Visual Functioning Questionnaire – 25 was administered to both patients in order to quantify improvement to quality of life with the new contact lenses.ResultsBoth patients were successfully fit with multifocal gas permeable contact lenses and reported decreased reliance on low vision aids as well as significant improvement in quality of life when wearing the contact lenses.ConclusionThe use of multifocal rigid gas permeable contact lenses in the low vision patient population may be an effective tool to make visually impaired patients, particularly presbyopic degenerative myopes, less reliant on low vision aids, thereby improving their quality of life.     

Scleral contact lenses in the pediatric population—Indications and outcomes

PurposeTo report the use of a custom-designed, scleral contact lens (SL) in the treatment of pediatric patients.MethodsThe medical records of all patients under 15 years of age fitted with SL from March 2018 through February 2020 were retrospectively reviewed. Ophthalmic diagnosis, prior surgical intervention, lens wearing failures, and duration of lens use are reported.ResultsLenses were dispensed to 18 patients (24 eyes). Main indications for SL fitting were refractive error correction (n = 18: keratoconus (KCN), traumatic corneal scarring, corneal transplant status, and aphakia) and ocular surface protection and optimization (n = 6: neurotrophic keratitis and chronic blepharokeratoconjunctivitis). Patient age ranged from 16 months to 14 years (mean, 9.9 ± 3.5 years (mean ± standard deviation (SD)). Patients fitted for surface disease indications were significantly younger, 8.8 ± 2.5 years. The mean maximal keratometry reading in patients with keratoconus was 64.0 ± 12.6 diopters (D). In six eyes with advanced KCN (Kmax 71.8 ± 11.0 D) and three eyes with traumatic scarring, SL use obviated the need for keratoplasty. Fifteen patients (83 %) continued scleral lens wear with a mean follow-up period of 9.2 ± 7.4 months. Complications included one case of corneal graft rejection and one corneal abrasion associated with lens insertion.ConclusionsThe goals of SL fitting in pediatric patients are visual rehabilitation and ocular surface protection. Pediatric patients with advanced keratoconus and traumatic corneal scarring are most appreciative of the benefits of scleral lenses. The challenges associated with SL fitting and the training process did not preclude long-term SL wear.     

Corneoscleral contact lenses for visual rehabilitation after keratoplasty surgery

PurposeTo report the use of corneoscleral lenses (CSL) in keratoconus patients who were unsatisfied with their visual outcomes after keratoplasty surgery.MethodsEleven consecutive cases with unsatisfactory vision with spectacles, due to irregular astigmatism, preferred to try CSL before SL due to handling or economic issues. An eye examination included refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count (ECC) and evaluation of corneal biomechanical parameters (corneal resistance factor, CRF; corneal hysteresis, CH; corneal-compensated intraocular pressure, IOPcc). The fitting process was performed using a diagnostic fitting set. Subjective visual quality and comfort, and CSL usage time were also recorded. Patients were monitored for 1 year.ResultsTwo patients presented intolerance to CSL. Therefore, nine patients (6 males and 3 females; the mean±SD age, 44.56 ± 17.33 years, range 27–82) were fitted with CSL. The log MAR visual acuity of these eyes improved significantly with CSL in relation to the best spectacle-corrected vision (0.02 ± 0.06 vs 0.22 ± 0.15, respectively; p = 0.007). Patients reported prolonged usage times (an average of 9.78 ± 1.99 h; range, 8–14). No significant adverse ocular effects or clinically relevant changes in ocular parameters (ECC, CH, IOPcc, central corneal thickness and keratometry; all p > 0.05), visual quality, comfort rating or usage time were found during the 1-year follow-up.ConclusionCorneoscleral lenses could be fitted in non-severe cases after keratoplasty surgery with optimal visual results as they can be a safe and healthy alternative option.     

The therapeutic and optical application of a rigid gas permeable semi-limbal diameter contact lens

Purpose

To evaluate the therapeutic and optical application of a semi-limbal diameter (S-LIM) rigid gas permeable (RGP) contact lens.

Method

A retrospective non-comparative case series of 14 consecutive patients (22 eyes) who were referred to one senior optometrist for the fitting of S-LIM contact lenses at Moorfields Eye Hospital. The cases comprised of 11 patients (17 eyes) with keratoconus, 1 patient (2 eyes) post-surgical ectasia from previous LASIK, 1 (1 eye) post-graft patient, and 1 patient (2 eyes) who required corneal protection secondary to lagophthalmos. These patients had failed previously with other lens designs because of lens intolerance, unstable vision, chronic 3 and 9 o’clock corneal staining, and inadequate corneal protection for the patient with lagophthalmos. A conventional method of using diagnostic lenses with fluorescein assessment was adopted in fitting the S-LIM lenses.

Results

The median duration of problems encountered with previous lenses was 4 years (range 0.5-10 years). The median visual acuity with the S-LIM lens was 6/9 (range 6/5-6/24). A median of 1 diagnostic lens (range 1-3 lenses) was required to achieve a satisfactory fit. At the last recorded follow-up, 10 patients (14 eyes) had no clinically observable problem and were wearing their lenses with a median wearing time of 8 h per day (range 1-18 h). The median duration of follow up was 6 months (range 2-18 months). One patient (1 eye) abandoned lens wear because of satisfactory unaided vision.

Conclusion

The use of a semi-limbal diameter lens can be an effective modality in patients with intolerance to other lens designs. However, lens modification from the standard design and the use of ocula lubricants are often required to optimise lens fit and to enhance tolerance.     

Exploring contact lens opportunities for patients above the age of 40 years

PurposeContact lenses offer a good option for patients with presbyopia, especially with improved optical designs available in modern multifocal contact lenses. Due to the ageing population there is good opportunity to increase contact lens penetration by managing these patients better. However, multifocal contact lenses achieve low penetration in the market.MethodsA questionnaire was administered to people aged above 40 years, to investigate their perceptions of contact lenses for presbyopia. Only people, with presbyopia, who were existing contact lens wearers or willing to try contact lenses were included. Participants were recruited from United Kingdom (UK), United States of America (USA), Netherlands, Germany, France, Spain and Italy.ResultsData from 1540 participants above the age of 40 years was collected, 57.9% were females and 42.1% males. Overall, 50.8% of the participants wore contact lenses, but contact lens wear was less common amongst older participants. Some data supported earlier studies, such as 6.1% wore gas permeable lenses. However, only 25% of the contact lens wearers used multifocal contact lenses. The reasons the participants wanted to wear contact lenses were similar to younger patient such as sports or cosmesis reasons. Reasons why participants had dropped out of contact lenses included discomfort and dry eye related issues. Poor visual performance with contact lenses was a reason to dropout of contact lenses for the older participants.ConclusionsThe study highlights some failings by eye care practitioners in the management of patients with presbyopia. It seems that patients of this age group are seeking suggestions and recommendations from their eye care practitioner including upgrading contact lenses and dual wear options. The day-to-day problems encountered by the contact lens wearers in this study seem to be, in the main, things that could be easily tackled by additional counselling and instruction from the eye care practitioners.     

Corneal shape changes induced by first and second generation silicone hydrogel contact lenses in daily wear

Purpose

To compare the corneal topographical changes induced by two first and second generation silicone-hydrogel (SiH) contact lenses after 3 months of daily wear (DW).

Methods

Prospective, consecutive case-series in which patients wore one of 3 different contact lenses (either the first generation SiH Focus Night & Day, the second generation SiH Acuvue Oasys or the monthly disposable Soflens 38 hydrogel lens as control group) on a DW basis for 3 months. Over-refraction, visual acuity, mean keratometry, corneal astigmatism, corneal eccentricity, superficial regularity and superficial asymmetry indices were monitored over the 3-month period.

Results

Nineteen eyes of 10 patients completed the study. Seven Focus Night & Day, 7 Acuvue Oasys and 5 Soflens 38 contact lenses were fitted. There were no significant changes between any of the parameters measured at the 3-month visit in any of the SiH groups (non-parametric Wilcoxon test, p > 0.05). However, the control group (Soflens 38) showed statistically significant changes regarding mean keratometry, corneal astigmatism and corneal eccentricity (p < 0.05). Three patients wearing the first generation SiH showed adverse events of different degree related to their high modulus of elasticity.

Conclusions

After 3 months of DW, wearers of first and second generation SiH lenses showed greater corneal stability than hydrogel monthly disposable contact lenses users regarding commonly used topographic corneal shape indices. However, complications related to the mechanical properties of first generation SiH were seen in three patients in the follow-up time.     

Fitting the post-keratoplasty cornea with hydrogel lenses

Purpose

We report two cases who have undergone penetrating keratoplasty (three eyes total), and who were fitted with hydrogel lenses.

Methods

In the first case, a 28-year-old male presented with an interest in contact lens fitting. He had undergone corneal transplantation in both eyes, about 5 years ago. After topographies and trial fitting were performed, it was decided to be fitted with reverse geometry hydrogel lenses, due to the globular geometry of the cornea, the resultant instability of RGPs, and personal preference. In the second case, a 26-year-old female who had also penetrating keratoplasty was fitted with a hydrogel toric lens of high cylinder in the right eye.

Results

The final hydrogel lenses for the first subject incorporated a custom tricurve design, in which the second curve was steeper than the base curve and the third curve flatter than the second but still steeper than the first. Visual acuity was 6/7.5 RE and a mediocre 6/15 LE (OU 6/7.5). The second subject achieved 6/4.5 acuity RE with the high cylinder hydrogel toric lens.

Conclusions

In corneas exhibiting extreme protrusion, such as keratoglobus and some cases after penetrating keratoplasty, curvatures are so extreme and the cornea so globular leading to specific fitting options: sclerals, small diameter RGPs and reverse geometry hydrogel lenses, in order to improve lens and optical stability. In selected cases such as the above, large diameter inverse geometry RGP may be fitted only if the eyelid shape and tension permits so. The first case demonstrates that the option of hydrogel lenses is viable when the patient has no interest in RGPs and in certain cases can improve vision to satisfactory levels. In other cases, graft toricity might be so high that the practitioner will need to employ hydrogel torics with large amounts of cylinder in order to correct vision. In such cases, the patient should be closely monitored in order to avoid complications from hypoxia.     

Correlation between long-term use of rigid gas permeable contact lenses and endothelial morphometric changes in keratoconus patients

PurposeThis study was conducted to evaluate the effects of long-term use of rigid gas-permeable (RGP) contact lenses on corneal endothelium in keratoconus (KC) patients using non-contact specular microscopy. In addition, the correlation between wearing duration of RGP lenses (years & hours /d) and endothelial morphometric changes in KC patients was performed. This may provide more useful data for clinical application of RGP contact lens.Study designThis study was a prospective, observational, comparative, hospital based, nonrandomized, cross-sectional, and quantitative study.Subjects and methodsThe study included 40 eyes of non-wearer contact lens KC patients (group 1) and 38 KC eyes with a long history of Rose K2 RGP contact lens wearing (group 2). The corneal endothelial morphology such as endothelial cell density (ECD); coefficient of variation of cell area (CV); percentage of hexagonal cells (HEX); and central corneal thickness (CCT) were evaluated in all patients using SP3000P Specular Microscope.ResultsThe study included 40 eyes of non-wearer contact lens KC patients (20 mild KC eyes and 20 moderate KC eyes) and 38 KC eyes with a long history of RGP contact lens wearing (18 mild KC eyes and 20 moderate KC eyes). The mean duration of RGP lenses wearing was 5.67 ± 3.481 years & 12.11 ± 2.698 h/d in mild KC eyes and 7.15 ± 5.294 years &13.65 ± 2.889 h/d in moderate KC eyes. Wearing duration in hours in mild KC eyes showed a significant moderate negative correlation with ECD (r = ?0.529, p = 0.024) and a moderate positive correlation with CV (r = 0.565, p = 0.015). In addition, wearing duration in years in moderate KC eyes showed a significant moderate negative correlation with ECD (r = ?0.465, p = 0.039) and moderate positive correlation with CV (r = 0.627, p = 0.003). However, wearing duration in hours in moderate KC eyes showed a significant moderate negative correlation with HEX only (r = ?0.490, p = 0.028). This study reported significant corneal thinning in contact lens wearer KC eyes in contrast to non-wearer KC eyes.ConclusionThis study documented a significant correlation between a long-term use of Rose K2 RGP using the three-point touch and corneal endothelial morphometric changes in KC patients. In addition, the current study confirmed a significant corneal thinning in RGP contact lens wearer compared to non-contact lens wearer KC patients. Further studies are recommended to evaluate the association between different RGP lens materials with different oxygen permeability transmissibility; different lens design types; different fitting methods; the duration of contact lens wear and the endothelial morphometric changes in KC patients.     

Corneal epithelial thickness and corneal curvature changes during the day: The effects of daily disposable contact lens wear

PurposeTo evaluate the changes in corneal epithelial thickness and corneal anterior and posterior curvatures during the day, and the effect of wearing daily disposable soft contact lenses.MethodsThirty-two healthy volunteers were enrolled in a randomized crossover study. At the baseline visit, corneal and epithelial thickness maps (OCT; Optovue, Inc., Fremont, CA, USA) and keratometric measurements (Pentacam, Oculus, GmbH, Germany) were performed in the morning and in the afternoon (8 hours after). Then, each subject was fitted with the following brands of daily disposable contact lenses in random order: Dailies Total 1 (Delefilcon A), Dailies Aqua Comfort (Nelfilcon A), TruEye (Narafilcon A) and Biotrue Oneday (Nesofilcon A) on different days. All fitted lenses had a power of −3.00 diopters (D). Measurements were repeated before putting the contact lens on and after an-eight-hour contact lens wear.ResultsWith no lens wear, the anterior topographic indices showed significant steepening [Kflat: p < 0.0001; Ksteep: p < 0.0001 and maximum keratometry value (Kmax): p = 0.04] and the corneal thickness significantly decreased in the central and temporal portion of the cornea in the afternoon. There were no significant changes in the posterior topographical indices and corneal epithelial thickness. With contact lens wear, no significant change occurred in the corneal and epithelial thickness, and the anterior and posterior curvatures during the day (all p values >0.05). There was no statistically significant difference in the epithelial thickness among the groups wearing different contact lens types (p > 0.05).ConclusionsAnterior corneal topographic indices steepen depending on the natural diurnal variations. Daily wear of soft contact lenses appears to mask this steepening. The corneal epithelial thickness is not affected by daily disposable soft contact lenses.     

An evaluation of corneal nerve morphology and function in moderate keratoconus.

PURPOSE: To investigate corneal nerve morphology and corneal sensitivity in keratoconus. METHODS: The central cornea of 13 subjects with keratoconus and 13 age-matched control subjects was assessed using in vivo confocal microscopy and corneal aesthesiometry. RESULTS: Significant differences in corneal nerve fibre density were found between the subjects with keratoconus and the control subjects (keratoconus versus control; 1018.3+/-489.6 microm versus 1820.7+/-789.5 microm; p = 0.006). The mean diameter of nerve fibres in the stroma was found to be greater in subjects with keratoconus compared to control subjects (keratoconus versus control; 10.2+/-4.6 microm versus 5.5+/-1.9 microm; p = 0.007). The orientation of corneal nerve fibres in the subjects with keratoconus appeared to be altered from the predominantly vertical orientation seen in the control subjects. Corneal touch threshold was found to be similar in the two groups, although the subjects with keratoconus using contact lens correction had reduced corneal sensitivity compared to the contact lens-wearing control subjects (keratoconus with contact lenses versus controls with contact lenses; 1.18+/-0.19 g/mm2 versus 0.98+/-0.05 g/mm2; p = 0.03). CONCLUSION: This study reveals significant reductions in nerve density in the keratoconic cornea. The thickened stromal nerve fibres observed in the keratoconic corneas may explain why prominent corneal nerves are often seen using slit lamp biomicroscopy in keratoconic patients.     

Assessing a modified fitting approach for improved multifocal contact lens fitting

Purpose: To compare the effectiveness of a modified and previous fitting guide for multifocal (MF) contact lenses that share a common optical design, lotrafilcon B, nelfilcon A, and delefilcon A, in current soft contact lens (CL) wearers needing presbyopia correction.Methods: This international multicenter, prospective, randomized, subject-masked study assessed the superiority of the modified guide relative to the previous guide as determined by the number of MF CLs needed to successfully fit each eye at the screening/fitting visit.Results: A total of 183 presbyopic subjects were randomized to fitting using the modified (n = 99) and previous (n = 84) MF CL fitting guides. The mean ± SD numbers of lenses required to fit each eye at the screening/fitting visit using the modified and previous fitting guides were 1.2 ± 0.5 and 1.4 ± 0.5, respectively. The least-squares mean difference (0.2) met predetermined criteria for superiority of the modified fitting guide. At the screening/fitting visit, 82.8% (164/108) and 65.1% (105/166) of presbyopic eyes were fit with one pair of MF lenses using the modified and previous guides, respectively, and 98.0% (194/198) of eyes were fit with 1–2 pairs of MF lenses using the modified guide. A higher percentage of eye care practitioners gave the highest ratings for ease of fit for the modified than for the previous fitting guide (63.6% [7/11] vs 33.3% [3/9]).Conclusions: The modified fitting guide was superior at reducing the number of MF lenses required to successfully fit each presbyopic patient.