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.     

Visual quality with corneo-scleral contact lenses after intracorneal ring segment (ICRS) implantation for keratoconus management

PurposeTo evaluate the visual quality results when fitting a corneo-scleral contact lens (CScL) after intracorneal ring segment (ICRS) implantation for keratoconus management.MethodsTwenty-seven eyes of 27 patients with keratoconus underwent ICRS implantation and had CScL fitted as their visual quality was unsatisfactory with their spectacles or contact lenses. Patients received a complete eye examination, refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count, and visual quality assessment using contrast sensitivity and aberrometry tests. A diagnostic trial set was used in the fitting process, and patients were assessed according to a standardised methodology, including subjective visual quality and comfort, and contact lens usage time. The follow-up period was one year.ResultsAfter fitting CScL, log-MAR visual acuity values improved significantly in relation to the best spectacle-corrected vision (0.22 ± 0.17 vs 0.00 ± 0.12; p < 0.001). Total high-order aberrations decreased 33% (2.62 ± 1.31 vs 1.75 ± 1.81 μm; p < 0.009) and the spatial frequencies of contrast sensitivity all improved (all p < 0.05). Furthermore, 70.37% of patients reported high ratings of subjective visual quality (favourable and very favourable) and prolonged usage times (11.78 ± 3.93 h). After wearing CScL for one year, no adverse ocular effects or clinically relevant changes in corneal parameters, visual quality, comfort ratings or usage time were found.ConclusionThis CScL appears to be an alternative reasonable option for keratoconic eyes with ICRS placement, providing an improvement in subjective visual quality.     

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.     

Optimizing correction of coma aberration in keratoconus with a novel soft contact lens

PurposeTo report on a second-generation prototype contact lens (modified lens) with enhanced optics to correct coma aberration and compare its performance with that of the prototype contact lens (conventional lens) used to optimise correction of coma aberration in keratoconus (KC).MethodsBoth lenses were designed as a set of standardised soft contact lenses (SCLs) with asymmetric powers along the posterior surface. The modified lens differs from the conventional lens in that the optical zone is decentred superiorly by 0.7 mm. The on-eye performance was compared between the SCLs and no-lens wearing in terms of manifest refraction, corrected distance visual acuity (CDVA), ocular aberrations, subjective quality of vision, and on-eye lens position relative to the pupil.ResultsThirty-four KC eyes were included. SCLs significantly decreased coma aberration compared to no-lens wear (none, 0.68 ± 0.27 μm; conventional lens, 0.37 ± 0.28 μm; modified lens, 0.19 ± 0.15 μm; P < 0.001), with the reduction in coma aberration being significantly greater with the modified lens than with the conventional lens (P = 0.018). No significant difference in manifest refraction or CDVA was found among the three conditions. Quality of vision was significantly better with the modified lens than with no SCL wear (P < 0.05) but no differences were found between the SCLs. The on-eye optical center position relative to the pupil was closer to the pupil centre using the modified lens than the conventional lens (P < 0.001).ConclusionOptimisation of the location of the optical zone in a standardised asymmetric SCL improves correction of coma aberrations and on-eye optical centration.     

New web-based algorithm to improve rigid gas permeable contact lens fitting in keratoconus

Purpose

To calculate and validate a new web-based algorithm for selecting the back optic zone radius (BOZR) of spherical gas permeable (GP) lens in keratoconus eyes.

Scleral lens after intracorneal ring segments in patients with keratoconus

Background

To report the use of scleral lens (ScCL) to improve vision in patients having keratoconus who had intracorneal ring segment (ICRS) surgery.

Corneo-scleral contact lens in a piggyback system for keratoconus: A case report

Purpose

We describe a case of fitting a corneo-scleral contact lens with a multi-aspheric geometry design (MAGD CScL) on top of a daily silicone hydrogel lens (piggyback system) for keratoconus management.

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.     

Soft contact lens-induced corneal deformation in the posterior corneal surface

ObjectiveThis case report aims to highlight the corneal deformation induced by soft contact lens (SCL) wear, which is accompanied by changes in not only the anterior but also the posterior surface of cornea.Case ReportCases are presented of two patients who wore non- planned replacement SCL for more than 15 years fabricated from materials with low oxygen permeability, sought a consultation with complaints of visual acuity loss in the both eyes. Anterior segment optical coherence tomography imaging demonstrated corneal deformation in the posterior as well as the anterior surface in both eyes of two patients, resulting in the diagnosis of corneal deformation induced by SCL wear. After the cessation of lens wear, there were improvements in visual acuity, anterior and posterior corneal higher-order aberrations, and changes in the anterior corneal shape, whereas the posterior corneal shape was improved in one case and remained mildly deformed in the other case.ConclusionWearing SCLs with low oxygen permeability for long time periods, could induce corneal deformation in patients, indicating the need for careful observation of changes in not only the anterior but also the posterior corneal surface.     

Visual quality with corneo-scleral contact lenses for keratoconus management

Purpose

To assess the visual quality achieved by fitting corneo-scleral contact lenses (CScL) for keratoconus management.

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.

Patterns of fitting cosmetically tinted contact lenses

Cosmetically tinted soft contact lenses are an attractive option for contact lens wearers. Data that we have gathered from annual contact lens fitting surveys demonstrate that those wearing tinted lenses are more likely to be female (4.6% of all soft lenses fitted vs. 1.6% for males; p < 0.0001) and younger (27 ± 11 years vs. 33 ± 13 years for those wearing non-tinted lenses; p < 0.0001). Tinted lenses tend to be worn more on a part-time basis and are replaced less frequently than non-tinted lenses. The decline in fitting tinted lenses over the past 12 years may be due to (a) the current limited availability of tinted lenses in silicone hydrogel materials and daily disposable replacement frequencies, which together represent a significant majority (78%) of new soft lenses fits today, (b) growing concerns among lens wearers and practitioners relating to the risks of complications associated with the wearing of tinted lenses, and (c) reduced promotion of such lenses by the contact lens industry.     

The influence of soft contact lens wear and two weeks cessation of lens wear on corneal curvature

IntroductionAccurate corneal measurements are crucial in corneal refractive surgery (CRS) to ensure successful outcomes. Soft contact lens (SCL) wear may result in changes to corneal curvature and structure. United States Food and Drug Administration (FDA) pre-operative guidelines recommend that prior to CRS, SCL wearers cease SCL wear for “at least two weeks before examination and treatment” [1]. Corneal curvature changes induced by SCL wear may take longer than two weeks to resolve.PurposeTo examine the effect of SCL wear on corneal curvature before and following two weeks SCL wear cessation. To explore the possible impact of different SCL materials and years of SCL wear.MethodsRetrospective data analysis, between a group of SCL wearers (SCL: n = 45); and a non-contact lens control group (NCL: n = 45). Corneal curvature parameters were measured using the Pentacam (Oculus, Germany), before and following two weeks cessation of SCL wear.ResultsNo significant differences in keratometry or Sagittal radius of curvature between SCL and NCL groups prior to or following SCL cessation. Tangential radius of curvature showed significant inferior steepening for the SCL group prior to SCL cessation (SCL vs. NCL; 7.77 ± 0.30 mm vs. 7.90 ± 0.30 mm; p = 0.04). Following two weeks cessation of SCL wear this appeared to have resolved.ConclusionsTwo weeks cessation of SCL wear appears sufficient for resolution of corneal curvature changes with modern SCL materials and years of SCL wear. However, further studies with longer lens deprivation periods are required to ensure stability for all SCL wearing patients.     

The effect of soft contact lens thickness in visual function after intracorneal ring segments surgery

Objective

To study the influence of soft contact lens (SCL) central thickness and material in keratoconus on visual function after intracorneal ring segment (ICRS) surgery.

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.

Theoretical fitting characteristics of typical soft contact lens designs

Purose

To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model.

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.     

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.     

The role of corneo-scleral junction in soft contact lens fitting: Case report on nanophthalmos

BackgroundNanophthalmos is rare developmental ocular condition characterized by a small eye with short axial length, high hyperopia and high lens to eye volume ratio due to arrested development of eye ball as a result of scleral inelasticity.ObservationsA 33 year old woman who presented with a complaint of blurring of distance and near vision in both eyes since childhood came to LV Prasad Eye Institute on July 2017. Best corrected visual acuity was 20/60 using soft contact lens +23.50 diopters for the right and left eyes. Axial lengths of two eyes were markedly shortened along with steep corneal curvatures. Visante anterior segment ocular coherence tomography showed a steep (convex) corneo-scleral junction (CSJ) which might be the reason for ill-fitting with conventionally estimated soft contact lens (SCL) parameters. Finally, selection of the customized hydrogel soft contact lens base curve close to flatter corneal curvature and small diameter showed characteristics of optimal lens fit.ConclusionThe corneo-scleral junction profile plays significant role in soft contact lens fitting. An eye with a profile of convex CSJ would require a lens with steeper curvature compared to conventional measurements. Cases of nanophthalmos would require observation of the profile with the help of optical coherence tomography in addition to measurement of corneal curvature prior to fitting soft contact lenses.