Effects of the rigid gas permeable contact lense use on tear and ocular surface among keratoconus patients

Purpose

To investigate changes in tear and ocular surface of patients with keratoconus using rigid gas permeable contact lenses (RGPCL) and compare them against keratoconus patients who were not using lenses as well as a control group of healthy subjects.

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.     

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.     

Cone location and correction of keratoconus with rigid gas-permeable contact lenses

Purpose

To evaluate the influence of cone location and corneal cylinder on RGP corrected visual acuities and residual astigmatism in patients with keratoconus.

Methods

In this prospective study, 156 eyes from 134 patients were enrolled. Complete ophthalmologic examination including manifest refraction, Best spectacle visual acuity (BSCVA), slit-lamp biomicroscopy was performed and corneal topography analysis was done. According to the cone location on the topographic map, the patients were divided into central and paracentral cone groups. Trial RGP lenses were selected based on the flat Sim K readings and a ‘three-point touch’ fitting approach was used. Over contact lens refraction was performed, residual astigmatism (RA) was measured and best-corrected RGP visual acuities (RGPVA) were recorded.

Results

The mean age (±SD) was 22.1 ± 5.3 years. 76 eyes (48.6%) had central and 80 eyes (51.4%) had paracentral cone. Prior to RGP lenses fitting mean (±SD) subjective refraction spherical equivalent (SRSE), subjective refraction astigmatism (SRAST) and BSCVA (logMAR) were −5.04 ± 2.27 D, −3.51 ± 1.68 D and 0.34 ± 0.14, respectively. There were statistically significant differences between central and paracentral cone groups in mean values of SRSE, SRAST, flat meridian (Sim K1), steep meridian (Sim K2), mean K and corneal cylinder (p-values < 0.05). Comparison of BSCVA to RGPVA shows that vision has improved 0.3 logMAR by RGP lenses (p < 0.0001). Mean (±SD) RA was −0.72 ± 0.39 D. There were no statistically significant differences between RGPVAs and RAs of central and paracentral cone groups (p = 0.22) and (p = 0.42), respectively. Pearson's correlation analysis shows that there is a statistically significant relationship between corneal cylinder and BSCVA and RGPVA, However, the relationship between corneal cylinder and residual astigmatism was not significant.

Conclusions

Cone location has no effect on the RGP corrected visual acuities and residual astigmatism in patients with keratoconus. Corneal cylinder and Sim K values influence RGP-corrected visual acuities but do not influence residual astigmatism.     

The use of rigid gas permeable contact lenses in children with myopic amblyopia: A case series

Purpose

To explore the safety profile and overall visual improvement over the course of RGP contact lens wear on children with unilateral or bilateral amblyopia resulting from myopia.

Fitting an MSD (Mini Scleral Design) rigid contact lens in advanced keratoconus with INTACS

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients.     

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.     

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.     

Corneo-scleral contact lenses in an uncommon case of keratoconus with high hyperopia and astigmatism

Purpose

To analyse the visual quality achieved by fitting corneo-scleral contact lenses (CScL) in an uncommon case of bilateral keratoconus, high hyperopia and astigmatism.

Posterior cornea and thickness changes after scleral lens wear in keratoconus patients

PurposeTo evaluate the changes in the corneal thickness, anterior chamber depth and posterior corneal curvature and aberrations after scleral lens wear in keratoconus patients with and without intrastromal corneal ring segments (ICRS).MethodsTwenty-six keratoconus subjects (36.95 ± 8.95 years) were evaluated after 8 h of scleral lens wear. The subjects were divided into two groups: those with ICRS (ICRS group) and without ICRS (KC group). The study variables evaluated before and immediately after scleral lens wear included corneal thickness evaluated in different quadrants, posterior corneal curvature at 2, 4, 6 and 8 mm of corneal diameter, posterior corneal aberrations for 4, 6 and 8 mm of pupil size and anterior chamber depth.ResultsThere was a statistically significant corneal thinning (p < 0.05) in the inferior region of the KC group and in the superior region of the ICRS group. No change (p > 0.05) in the anterior chamber depth was found. The KC group showed a steepening (p < 0.05) in the temporal quadrant and a flattening that mainly affected to the superior-nasal quadrant. The ICRS group showed a steepening (p < 0.05) that mainly affected to the superior-nasal quadrant. Regarding posterior corneal aberrations, only changes (p < 0.05) in Z4 for 8 mm and Z8 for 4 mm were found in the KC group.ConclusionsShort-term scleral lens wear showed a thinning of the cornea and changes in the posterior corneal curvature affects different regions in keratoconus patients with and without ICRS.     

Semi-automatic measurement of rigid gas-permeable contact lens movement in keratoconus patients using blinking images

Purpose

To introduce a method for estimation of the rigid gas-permeable contact lens (RGP) movement.

Predicting initial base curve of the rigid contact lenses according to Javal keratometry findings in patients with keratoconus

PurposeTo find an appropriate correlation between the base curve (BC) of rigid gas permeable (RGP) contact lenses and manual keratometry findings in Iranian patients with keratoconus (KCN) in order to simplify the fitting process, reduce the time, and lower the costs.MethodThis retrospective study was done in 121 eyes of 69 patients with KCN fitted with a specific trial set of RGP contact lenses over a 7-year period. The specifications of the final lens parameters included power, total diameter (1), and BC, the first two of which were fixed in all of the lenses in the trial set while BC was changed in 0.1-mm steps. Javal keratometer was used to measure keratometric values. The final fit assessment was performed based on the standard criterion of "three-point touch".ResultSingle and multiple linear correlations were done and the result was the following equation: BC = 2.455 (constant of the final multiple regression model) + 0.280 (steep keratometry) + 0.368 (flat keratometry) + 0.047 (corneal astigmatism)ConclusionThe advantages of this study include simplifying the RGP fitting process, reducing the examination time, lowering the costs, enhancing the confidence of the examiners and patients, easier lens fitting in remote places where more advanced devices are not accessible.     

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.     

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.