Preeji S. Mandathara

Boston ocular surface prosthesis: An Indian experience

Context: Boston ocular surface prosthesis (BOSP) is a scleral contact lens used in the management of patients who are rigid gas permeable (RGP) failures as with corneal ectasias such as keratoconus and in those patients who have ocular surface disease such as Stevens–Johnson syndrome (SJS). Aim: To report utilization of BOSP in a tertiary eye care center in India. Materials and Methods: We retrospectively reviewed charts of 32 patients who received BOSP from July 2008 to May 2009. Indications for fitting these lenses, improvement in visual acuity (VA) before and after lens fitting and relief of symptoms of pain and photophobia were noted. Paired t-test was used for statistical analysis using SPSS version 16.0 for Windows. Results: Thirty-two patients (43 eyes) received these lenses. These consisted of 23 eyes of 17 patients who failed RGP trials for irregular astigmatism and corneal ectasia such as keratoconus and post radial keratotomy and scar and 20 eyes of 15 patients with SJS. Mean age of RGP failures was 27.94 years. Pre- and post-BOSP wear mean LogMAR VA was 1.13 and 0.29, respectively, in RGP failures. The P value was statistically significant (P < 0.001). In patients with SJS, LogMAR VA was 0.84 ± 0.92 before and 0.56 ± 0.89 after lens wear. The P value was statistically significant (P < 0.001). VA improved by >2 lines in 7/20 eyes (35%) with SJS, with improvement in symptoms. Conclusion: BOSP improves VA in patients who have irregular astigmatism as in ectasias and RGP failures and improves vision and symptoms in patients with SJS.

Fluid filled scleral contact lens in pediatric patients: challenges and outcome.

PURPOSE To study the indications and the challenges while fitting scleral contact lens (ScCL) filled with fluid prior to lens insertion in pediatric patients. METHODS We retrospectively reviewed charts of patients of 16 years or less who received ScCL (PROSE - Prosthetic Replacement of the Ocular Surface Ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA) that were filled with fluid (Normal saline) before lens insertion during July 2006 to April 2010. The main goal of ScCL fitting was to improve vision in patients having keratoconus (KC) and improve the ocular microenvironment in ocular surface disease (OSD). Visual acuity before and after lens wear was noted. RESULTS Fluid-filled ScCL were dispensed to 15 patients (20 eyes). The indications for ScCL fitting were KC (n = 3 eyes), Stevens Johnson syndrome (SJS, n = 13 eyes), radiation keratopathy (n = 1 eye), combined KC and SJS (n = 1 eye) and KC and vernal keratoconjunctivitis (VKC, n = 2 eyes). Mean age of the patients was 12.85 years. The average daily lens wear was 9 h. The vision improved by 2 lines or more in 85% and dropped by 2 lines or more in 45% eyes after 4 h of lens wear due to tear debris collection. None of the patients had any complications. Patients were self sufficient inserting and removing ScCL. Two patients had broken lenses during the follow-up. CONCLUSIONS ScCL are useful for pediatric patients who have OSD, irregular astigmatism or the two coexisting; KC combined with VKC or SJS, helping to maintain the health of the ocular surface and improves vision in these patients.

Contact lens in keratoconus.

Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

Fluid-filled scleral contact lenses in vernal keratoconjunctivitis.

Objectives: The purpose of this study is to report on the use of fluid-filled scleral contact lenses (F-ScCL) in patients with vernal keratoconjunctivitis (VKC). Methods: We retrospectively reviewed charts of four patients who had worn F-ScCL (PROSE, Boston Foundation for Sight, Needham Heights, MA) from July 2006 for VKC with two associated conditions; keratoconus and limbal stem-cell deficiency (LSCD). Any previous refractive correction or complications were noted. The main goal of fitting F-ScCL was to improve visual acuity in keratoconus and to improve the ocular microenvironment in LSCD. Visual acuity before and during lens wear and the average wearing time in hours per day was noted. Results: Four patients (7 eyes) with VKC wore F-ScCL for associated keratoconus (n=5 eyes), LSCD (n=2 eyes). The mean age of the patients was 17. 5 years. The LogMAR visual acuity was 0.4 and 0.18 before and during lens wear, respectively, at a mean follow-up of 14.8 months. The average lens wear was 8.30 hrs per day. Two patients developed acute hydrops at 2 and 12 months of lens wear and underwent descematopexy. Visual acuity with F-ScCL reduced by more than two lines because of the scar of healed hydrops. Of the 3 patients with keratoconus, 1 patient had used a piggy back lens system for 2.5 years before F-ScCL wear, and 2 patients had failed with rigid gas-permeable lens trial lenses. Conclusions: With coexisting keratoconus and VKC, F-ScCL improves vision and helps to maintain the health of the ocular surface.

Prevalence of contact lens related complications in a tertiary eye centre in India

AIM To determine the prevalence of contact lens related complications in a tertiary eye care centre in India. METHODS A retrospective review of the charts of 1255 patients who visited our contact lens clinic during 2001-2004 was conducted. The inclusion criteria included patients of at least 18 years of age, having refractive errors and keratoconus. Exclusion criteria included previous corneal surgeries and pediatric patients. 190 subjects with lens related complications were identified from among 923 patients who were using lenses. RESULTS The prevalence of contact lens complications was 20.58%. Females with complications were more common (59.47%). The complications were more common in students. The most common complications were contact lens induced papillary conjunctivitis (CLPC) (6.39%), corneal vascularisation (4%), and superficial punctate keratitis (SPK) (3.5%). The total complications were less prevalent in patients wearing rigid gas permeable (RGP) lenses as compared to soft contact lenses. Infectious keratitis was noted in 8 eyes. Pseudomonas aeuroginosa was the most common organism isolated. The average daily wear with RGP lenses was 11.04±3.7h and 10.96±3h with soft contact lens. The highest number of complications was noted in 47.89% patients who were wearing lenses for excess of 11h. The number of patients with complications arising due to sleeping with the lenses was 74 (38.95%). CONCLUSION Prevalence of contact lens complications was more in soft contact lens wearers compared to RGP wearers. CLPC was the most common complication followed by vascularisation and SPK.

Evaluation of corneal elevation and thickness indices in pellucid marginal degeneration and keratoconus

Purpose To determine and compare corneal elevation and thickness indices, thereby formulating a reliable index to distinguish eyes with pellucid marginal degeneration (PMD) from keratoconus eyes and normal (control) eyes. Setting LV Prasad Eye Institute, Hyderabad, India. Design Initial model‐building retrospective study. Methods Anterior and posterior corneal elevations and thickness indices were obtained from the Orbscan IIz topographer. These values were analyzed and compared between PMD patients, keratoconus patients, and control subjects. Results Of the indices, the mean values of anterior elevation (AE), ratio of the AE to the anterior best‐fit sphere, ratio of the average power values of nasal quadrant to the average power values of inferior quadrant, and difference between maximum keratometry (K) and minimum K were significantly different between the 3 groups (P<.05). The highest area under the receiver‐operating‐characteristic (AROC) curve in discriminating PMD from keratoconus was for asphericity (0.974; cutoff ≥−0.07; sensitivity 93.3%; specificity 90.6%) followed by the ratio of average power values of the nasal and temporal quadrants to the average power values of the inferior and superior quadrants (Avg NT(D)/IS(D)) (0.959; cutoff ≥1.005; sensitivity 96.7%; specificity 90.6%). The PMD index (AROC curve, 0.935), with a cutoff of 3.45 or higher had 90% sensitivity and 93.7% specificity to distinguish PMD from keratoconus and had 100% sensitivity and 100% specificity to distinguish PMD from control eyes, with a cutoff of 2.46 or higher (AROC curve, 1.000). Conclusions The PMD index appeared to be highly sensitive and specific for diagnosing PMD. Asphericity and Avg NT(D)/IS(D) were clinically relevant in discriminating PMD from other groups. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

RGP contact lens fitting in keratoconus using FITSCAN technology

PURPOSE To 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 METHODS A 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. RESULTS Eighty-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 0.22mm 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. CONCLUSION Our study showed that selecting the BC of the initial trial lens 0.22mm steeper than the FITSCAN calculated base curve, may help to reduce the complexity of RGP contact lens fitting in keratoconus.

Scleral lens for keratoconus: technology update.

Scleral lenses are large diameter lenses which rest over the sclera, unlike the conventional contact lenses which rest on the cornea. These lenses are fitted to not touch the cornea and there is a space created between the cornea and the lens. These lenses are inserted in the eyes after filling with sterile isotonic fluid. Generally, scleral contact lenses are used for high irregular astigmatism as seen in various corneal ectatic diseases such as keratoconus, pellucid marginal degeneration, or/and as liquid bandage in ocular surface disorders. In this article, we review the new developments, that have taken place over the years, in the field of scleral contact lenses as regard to new designs, materials, manufacturing technologies, and fitting strategies particularly for keratoconus.

Scleral contact lenses in the management of pellucid marginal degeneration

PURPOSE To assess visual improvement with scleral lenses (PROSE, prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sightight, USA) in patients with Pellucid marginal degeneration (PMD). METHODS This is a single-center, retrospective case-series involving patients with clinical PMD who underwent scleral lens-PROSE trial for improvement of visual acuity, from January 2009 to December 2012 at a tertiary center in India. Scleral lenses with different front surface eccentricities (FSE) were tried for improvement of visual acuity. Snellen visual acuity before and with PROSE wear was noted. Complications with PROSE wear to follow-up were noted. RESULTS PROSE was dispensed to 12 patients (20 eyes) out of 19 patients having PMD. Location of PMD was inferior in fourteen and superior in two eyes. Four eyes had co-existing keratoconus. Nine were males and three were females. The indications for scleral lens were lens popping-out, failure of piggy-back contact lens and RGP failure. LogMAR Visual acuity improved significantly from 0.45±0.31 pre-PROSE to 0.05±0.08 post-PROSE (p=0.0001). The FSE ordered was 0.6 in 17 eyes, 0.3 in one eye and 0.8 in two eyes. Three patients had hydrops over follow-up; two patients underwent keratoplasty and one was managed conservatively with steroids and hyperosmotic agents. Seven patients did not order PROSE: reasons were - no perceived improvement in visual acuity (n=2), wanted to decide (n=2), continued glasses (n=1) and continued RGP contact lens (n=1). One patient had difficulty with self lens insertion. CONCLUSION PROSE improves visual acuity in PMD; three patients developed hydrops over follow-up.

Change in vault during scleral lens trials assessed with anterior segment optical coherence tomography

PURPOSE To assess the change in vault during scleral lens fitting with anterior segment optical coherence tomography (AS-OCT). METHODS This study comprised of patients who had AS-OCT performed after 1h and 4h of scleral lens wear (PROSE, prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA). Vault was measured on AS-OCT as the distance between the front surface of the cornea in the center and the back surface of the scleral lens. RESULTS Fifty eyes of 41 patients were analyzed. The main indications for scleral lens trial were ectasia (keratoconus, post surgery) (n=20 eyes) and ocular surface disease (OSD - Stevens - Johnson syndrome, dry eyes and limbal stem cell deficiency) (n=30 eyes). Mean age of the patients was 31.4 years. Twenty were males. The diameter of the scleral lens ranged from 16mm to 18.5mm. Vault measurements reduced in 45/50 eyes (90%), remained same (n=2) or increased (n=3). Overall mean vault decreased from 680±421μm at 1h to 589±355μm (p=<0.001) at 4h of lens wear. Mean vault in ectasia was 759±574μm and 634±455μm (p=0.02) at 1h and 4h of lens wear respectively. In OSD group, mean vault was 626±276μm and 558±273μm (p<0.01) at 1h and 4h of lens wear respectively. Average reduction in the vault was 125μm in ectasia and 68μm in OSD group. CONCLUSION Vault reduced significantly after 4h of lens wear during scleral lens trial indicating that the final assessment of the scleral lens may be done after 4h of lens wear.