Lipid-based eye drop formulations for the management of evaporative dry eyes.

Dry eye disease is a progressive prevalent ocular surface disorder that arises from various factors and is characterized by insufficient quality and/or quantity of tears. The underlying pathophysiology is intricate and can progress to chronic, difficult-to-treat conditions. Multiple strategies and therapeutic approaches are utilized in its management that target one or more etiopathological components of dry eyes, which may include aqueous tear deficiency or evaporative dry eyes. The primary focus of this paper is on treatment alternatives that utilize lipids for the treatment of evaporative dry eyes. This may arise from either abnormal lipid production or inadequate lipid spreading caused by meibomian gland dysfunction. The hypothesis behind the development of these lipid-containing eye drops is that if they can imitate the lipid layer, they may be able to help in the management of the signs and symptoms of evaporative dry eyes. The lipids used in commercial formulations for dry eyes are mineral oil, castor oil, phospholipids, omega-3 fatty acid, and medium-chain triglycerides. The literature suggests the potential of lipid-containing eye drops to alleviate some of the signs and symptoms and enhance the quality of life for individuals suffering from evaporative dry eyes.

Antimicrobial Efficacy of an Ultraviolet-C Device against Microorganisms Related to Contact Lens Adverse Events.

The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2) was used. Pseudomonas aeruginosa, Staphylococcus aureus, Fusarium solani, and Candida albicans agar plate lawns were exposed to the device beams for 15 and 30 s at 8 mm distance. Following the exposure, the diameter of the growth inhibition zone was recorded. Contact lenses made of Delfilicon-A, Senofilicon-A, Comfilicon-A, Balafilicon-A, Samfilicon-A and Omafilicon-A and a commercially available contact storage case was used. They were exposed to bacterial and fungal strains for 18 h at 37 °C and 25 °C respectively. After this, the samples were exposed to UVC for 30 s at 8 mm distance to determine the antimicrobial efficacy. Samples were then gently washed and plated on appropriate agar for enumeration of colonies. The UVC exposure reduced microbial growth by 100% in agar lawns, and significantly (p < 0.05) reduced microbial contamination to contact lenses and cases, ranging between 0.90 to 4.6 log. Very short UVC exposure has high antimicrobial efficacy against most of the predominant causative microorganisms implicated in contact lens related keratitis. UVC could be readily used as a broad-spectrum antimicrobial treatment for lens disinfection.

Bacterial Dye Release Measures in Response to Antimicrobial Peptides.

Assessment of bacterial dye release following exposure to antimicrobial peptides (AMPs) provides a detailed understanding regarding their interaction with the inner and outer membrane of bacteria, and the leak of bacterial intracellular materials. This underpins the overall antimicrobial mechanism of these membrane-active peptides. DiSC3(5) is a membrane potential sensitive dye and can characterize the changes in bacterial membrane potential following exposure to AMPs (see Note 1). SYTOX Green is a nucleic acid stain that enters the cell upon loss of membrane integrity after exposure to AMPs and binds to DNA. SYTO9 is another nucleic acid stain, whereas propidium iodide (PI) is a fluorescent intercalating agent that can be used to stain cells and nucleic acids. Both of these stains are widely used to monitor the viability of bacteria following exposure to AMPs. This chapter describes the methods of using these as bacterial dye release experiments for assessment of the antimicrobial mechanism of AMPs.

Prosthetic replacement of the ocular surface ecosystem for corneal irregularity: Visual improvement and optical device characteristics.

PURPOSE: To describe patterns of prescribing Prosthetic Replacement of Ocular Surface Ecosystem (PROSE) in irregular corneas and compare various components of lens design. METHODS: Design: Retrospective, observational case series. 244 eyes of 173 patients with keratoconus (n=178), pellucid marginal degeneration (n=21), keratoglobus (n=6), following refractive surgery (n=19) and following keratoplasty (n=20) fitted with the PROSE device were retrospectively analyzed. Simulated keratometry value along the steep meridian (Steep-K) and anterior chamber depth (ACD) were measured using Scheimpflug imaging. Improvement in visual acuity and parameters of lens design such as vault, front surface eccentricity (FSE) and toricity were analyzed and compared across all conditions. RESULTS: PROSE improved visual acuity, both uncorrected (median, 1.30 logMAR) and spectacle-corrected (median, 0.60 logMAR), to a median of 0.22 logMAR. Positive correlation was observed between Steep-K and ACD with lens vault, especially in keratoconus. Multiple regression analysis established ACD as the most reliable factor while choosing vault. FSE value of 0.6 was the most common across diagnostic subgroups. The distribution of FSE values did not differ between keratoconus patients with Steep keratometry of <60D or those >60D. In every diagnostic subgroup, at least 20% of eyes required a lens design of with-the-rule toricity of haptic. CONCLUSION: The PROSE device resulted in significant improvement in vision in this population. A trend of prescribing higher lens vault with increased keratometry value was evident especially in keratoconus. ACD appeared to be more important than Steep K in vault selection. An FSE of 0.6 and vertical peripheral lens toricity were used most frequently in this subset of patients.

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. METHODS: Two eyes of two keratoconus patients fitted with ScCL (PROSE - prosthetic replacement of the ocular surface ecosystem, USA) after having undergone ICRS surgery are reported as noncomparative interventional case series. The ICRS implanted were INTACs and kerarings. Indications, visual acuity with ScCL, complications and follow-up are reported. RESULTS: Case 1 underwent ScCL trial as he was referred for keratoplasty for being contact lens intolerant after ICRS surgery. Case 2 was intolerant to both corneal rigid gas permeable (RGP) lens and soft contact lens (SCL). 18.5 and 18mm diameter ScCLs were dispensed to Case 1 and 2 respectively. The ScCLs had adequate corneal clearance with no corneal touch. There was no staining of the cornea or vascularization with the lens use. Case 1 complained of double images during trial with different Front surface eccentricity (FSE). A ScCL that did not cause diplopia was ordered. At four months of lens wear, the patient had diplopia with ScCL, which cleared when second lens with changed FSE was dispensed. Case 2 used SCL for five years before ScCL was fitted. He used the same ScCLs for five years. ScCL use resulted in improved comfort and visual acuity of 20/20. No complications were noted. CONCLUSIONS: ScCL may be tried in patients who have ICRS and are intolerant to corneal RGP or SCL and before subjecting such patients to keratoplasty.

Role of Scleral Contact Lenses in Management of Coexisting Keratoconus and Stevens-Johnson Syndrome.

PURPOSE: To report the rare coexistence of keratoconus and Stevens-Johnson syndrome (SJS) managed with scleral contact lenses (ScCLs). METHODS: This is a retrospective case series. Five patients (9 eyes) who had coexisting SJS and corneal ectasia were identified from the database during the 2-year period. Diagnosis of SJS was based on a positive history of drug reactions, signs of ocular surface disease, and the presence of keratinization of lid margins. Keratoconus was diagnosed by slit-lamp biomicroscopy. RESULTS: Five eyes of 3 patients had coexisting SJS and keratoconus and were dispensed with ScCLs (PROSE, prosthetic replacement of the ocular surface ecosystem; Boston Foundation for Sight, Needham Heights, MA). All these patients had photophobia. Visual acuity improved in all these patients with ScCL wear. Two patients (4 eyes) were excluded from this study because they had SJS with generalized corneal thinning from limbus to limbus, corneal opacification, and pannus. One patient developed deep vessels in the cornea on prolonged ScCL wear. Reduction in the ScCL wear schedule and change of material with a higher Dk resulted in regression of vascularization. Case 3 developed conjunctival congestion and was uncomfortable wearing ScCLs, although visual acuity was 20/40. He discontinued using ScCL wear. CONCLUSIONS: Keratoconus, a noninflammatory condition of the cornea coexisted with inflammatory SJS. Managing such patients with ScCLs may improve vision and comfort.

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.

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.

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.

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.

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.

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.

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.