Gas-permeable Scleral Lenses Research Articles

The Boston Scleral Lens in the treatment of pediatric patients

To report the use of a custom-designed, fluid-ventilated, gas-permeable scleral lens in the treatment of patients under 13 years of age. We retrospectively reviewed the medical records of all patients under 13 years of age who were fitted with the Boston Scleral Lens at the Boston Foundation for Sight from January 1996 through June 2006. Age, sex, ophthalmic diagnosis, systemic diagnosis, prior surgical intervention, complications, lens fit and wearing failures, and duration of lens use are reported. Boston Scleral Lenses were fitted in 47 eyes of 31 patients referred after failure of conventional therapy. Patients ranged in age from 7 months to 12.92 years (mean, 7.75 years) at time of fitting. There were 16 girls and 15 boys in this group. The mean duration of documented scleral lens use was 24 months (range, 0-85 months). A broad range of refractive and ocular surface disorders was treated with this modality, with the vast majority of patients having ocular surface disease (27/31, 87%) rather than refractive disorders (4/31, 13%). Congenital corneal anesthesia syndromes and Stevens-Johnson syndrome each accounted for over one-third of the patients. The Boston Scleral Lens is a custom-designed, fluid-ventilated, rigid gas-permeable scleral lens that vaults the cornea retaining a pool of oxygenated artificial tears over the corneal surface. The Boston Scleral Lens is a treatment option, after failure of conventional therapy, for a broad range of ocular surface and refractive disorders in the pediatric age group. Pediatric ophthalmologists should be aware of this treatment modality, particularly in the management of severe ocular surface disease.

Use of Fluid-Ventilated, Gas-Permeable Scleral Lens for Management of Severe Keratoconjunctivitis Sicca Secondary to Chronic Graft-versus-Host Disease

Keratoconjunctivitis sicca (KCS) occurs in 40%-60% of patients with chronic graft-versus-host-disease (cGVHD) after allogeneic hematopoietic cell transplantation. Although immunosuppressive therapy is the primary treatment of chronic GVHD, ocular symptoms require measures to improve ocular lubrication, decrease inflammation, and maintain mucosal integrity. The liquid corneal bandage provided by a fluid-ventilated, gas-permeable scleral lens (SL) has been effective in mitigating symptoms and resurfacing corneal erosions in patients with KCS related to causes other than cGVHD. We report outcomes in 9 consecutive patients referred for SL fitting for cGVHD-related severe KCS that was refractory to standard treatments. All patients reported improvement of ocular symptoms and reduced the use of topical lubricants after SL fitting resulting from decreased evaporation. No serious adverse events or infections attributable to the SL occurred. The median Ocular Surface Disease Index improved from 81 (75-100) to 21 (6-52) within 2 weeks after SL fitting, and was 12 (2-53) at the time of last contact, 1-23 months (median, 8.0) after SL fitting. Disability related to KCS resolved in 7 patients after SL fitting. The use of SL appears to be safe and effective in patients with severe cGVHD-related KCS refractory to conventional therapies.

Use of Fluid-Ventilated, Gas-Permeable Scleral Lens (SL) for Management of Severe Keratoconjunctivitis Sicca Secondary to Chronic Graft-Versus-Host Disease.

Dry eyes or keratoconjunctivitis sicca (KCS) occur in 50 % of patients (pts) with chronic graft-versus-host-disease (cGVHD) after allogeneic hematopoietic cell transplantation (HCT) and may represent the only, or most significant, clinical manifestation of cGVHD in some pts. Artificial tears, long-acting ocular lubricants, punctal plugs, ophthalmic cyclosporine, topical corticosteroids, moisture chamber eyewear and oral cholinergic agents are the primary supportive therapies of ocular cGVHD. The liquid corneal bandage provided by a fluid-ventilated, gas-permeable scleral lens (Boston Scleral Lens, BSL) has been effective in mitigating symptoms and resurfacing corneal erosions in pts with a variety of causes of KCS refractory to conventional therapies. Here we report outcomes in 9 pts with cGVHD after related and unrelated HCT who had severe KCS treated by fitting a BSL because of debilitating ocular discomfort, visual impairment, or keratopathy despite systemic and local therapies and other supportive care. Diagnoses at time of HCT were CML (n=3), MDS (n=2), AML (n=1), AA (n=1), CLL (n=1) and MM (n=1). Median pt age at the time of SL fitting was 56 (range, 25–64) yrs. All pts had prior cGVHD involving multiple sites that required immunosuppression therapy (IS) with prednisone, +/− calcineurin inhibitors, +/− mycophenolate mofetil or other therapies. Manifestation of cGVHD other than eyes at the time of SL fitting were skin (n=2), mouth (n=5), liver (n=3), GI (n=1), lungs (n=1) and vagina (n=1). At the time of SL, 7 pts were receiving IS and 2 pts had discontinued all IS because of resolution of other manifestation of cGVHD. The response to the SL was assessed by patient-reported ocular disability and use of ancillary eye care, and by use of the Ocular Surface Disease Index (OSDI) in 5 pts. The OSDI is a valid and reliable tool used to assess severity of dry eye symptoms and vision-related function on a 0–100 scale, with higher scores correlating with increasing symptom severity and vision-related disability. Table below presents patients-reported outcomes. The use of the BSL led to ocular improvement in all cases. No serious adverse events or infections attributable to the BSL occurred. The median OSDI available improved from 87.7 to 20.8 within 2 weeks of BSL fitting and was 12.5 (4.2–52.7) at the time of last contact, 8–23 months (median, 15.2) after BSL fitting. Seven pts were no longer disabled by KCS after the BSL. All 9 pts reported reduced use of artificial tears, and 2 of 3 who were using moisture chamber eye glasses pre BSL were able to discontinue them. One pt had significant difficulty inserting the BSL, even with assistance. We conclude that BSL can be a safe and effective procedure for pts suffering from severe cGVHD-related KCS that is refractory to other therapies.No. of Patients9Artificial Tear Use (Times per day, N)- Before fitting Scleral Lens (SL)> 100- After fitting SL (median, range)3 (0–50)Punctal Plugs (times replaced, N)- Before fitting SL (median, range)3 (1–>6)- After fitting SL1 (1 pt)Subjective Assessment of Disability- Before fitting SLYes (7 pts)- After fitting SLYes (1 pt)

Fluid-Ventilated, Gas-Permeable Scleral Contact Lens Is an Effective Option for Managing Severe Ocular Surface Disease and Many Corneal Disorders That Would Otherwise Require Penetrating Keratoplasty

To examine the diagnostic indications and relative merits of a fluid-ventilated, gas-permeable scleral lens for improving vision impaired by irregular astigmatism and for providing a therapeutic environment for managing severe ocular surface disease. After a review of scleral lens development and a description of current design and manufacturing innovations, indications for fitting the Boston Scleral Lens were evaluated based on a retrospective review of all available records of patients fitted with this device, and outcome experiences were described. A total of 875 eyes of 538 patients were fitted with the fluid-ventilated, gas-permeable scleral lens during the past 18 years. Most patients were fitted in the past 4 years. Indications included managing severe ocular surface disease and rehabilitating vision impaired by irregular astigmatism associated with corneal disorders. Rigid gas-permeable contact lenses either were not tolerated or were contraindicated in all eyes. Outcomes included improved vision and reduced ocular pain and photophobia associated with severe ocular surface disease. Scleral lenses promoted healing of persistent epithelial defect (PED) refractory to other treatments and prevented PED recurrence in stem cell-deficient and neurotrophic corneas. Microbial keratitis occurred in 4 of 22 eyes treated with extended scleral lens wear for PED after penetrating keratoplasty. The fluid-ventilated, gas-permeable scleral lens is an important front-line tool for managing many corneal disorders refractory to other treatment measures or otherwise requiring keratoplasty.

Gas permeable scleral lenses as a conservative treatment option for extreme corneal ectasias and severe dry eye

Due to their exclusive scleral contact zone, non-ventilated gas permeable scleral contact lenses can be used to correct extreme keratectasia, even if corneal fitted contact lenses failed previously. As the gap between the scleral lens and the cornea is filled with fluid substitutes, they also can be used for patients with severe aqueous-deficient dry eyes. PATIENTS, MATERIAL AND METHOD: Scleral lens fitting was attempted in 13 eyes (9 patients, group I) of patients with extreme corneal ectasia and 9 eyes (5 patients, group II) with severe ocular surface disease. Best corrected visual acuity, keratometry, Schirmer's test, foreign body sensation, and total daily lens wearing time were recorded prior to and after scleral lens fitting. Scleral lenses were successfully fitted and used on a long-term basis in 6 of 13 eyes (4 patients) of group I and 4 of 9 eyes of group II. In 9 eyes visual acuity increased by at least 2 lines, but long-term lens wear was not possible due to severe foreign body sensation or fornix shortening. Modern gas permeable scleral lenses can successfully be used for nonsurgical rehabilitation of severe corneal ectasia and dry eyes.

Cicatricial Pemphigoid and Dry Eye

Cicatricial pemphigoid is the most common of the immunobullous disorders causing conjunctival cicatrization and is an autoimmune disease in which the ocular component of the immunopathology is directed at the conjunctival basement membrane. The disease is usually bilateral and more common in females, with most cases occurring between 30–90 years, and most often in the seventh decade. The disease occasionally occurs in children. Tear deficiency is a major cause of symptoms, although loss of vision is usually due to surface failure before the onset of aqueous tear deficiency, which occurs late in the progression of the disease. Management of the dry eye must be integrated with the management of the other components of both the ocular surface disease and inflammation. Management requires plastic surgery for the lid and lash malposition, tetracyclines and lid hygiene for the accompanying blepharitis. For the dry eye, the use of lubricants without preservatives is important, to avoid toxicity, and lubricant ointment is helpful for the relief of symptoms in terminally dry eyes without the capacity for surface wetting. Contact lenses, either large limbal diameter rigid gas permeable or gas permeable scleral lenses, are useful for treating dry eye and improving vision in some patients. Control of the conjunctival inflammation is mandatory to prevent disease progression and usually requires systemic immunosuppressive therapy.

The Boston Scleral Lens in the management of severe ocular surface disease

Fluid-ventilated, gas-permeable scleral lenses are a valuable front-line tool in the management of severe ocular surface disease. In addition to enhancing vision, they have the potential to reduce greatly the disabling ocular pain and photophobia associated with SJS, TEN, and ocular cicatricial pemphigoid. They are also useful in healing some PEDs that are refractory to all other treatment strategies and in reducing PED recurrence in stem cell-deficient and neurotrophic corneas. The therapeutic benefits of these lenses are provided by the oxygenated aqueous environment they create over the corneal epithelium. The oxygenated precorneal fluid compartment that is maintained at neutral pressure protects the epithelial surface from the desiccating effects of exposure to air and the friction generated by blinking and avoids the shearing forces generated during the blink-induced movement of soft lenses.

Treatment of persistent corneal epithelial defect with extended wear of a fluid-ventilated gas-permeable scleral contact lens

PURPOSE: To report treatment of persistent corneal epithelial defects unresponsive to other therapies by extended wear of a fluid-ventilated gas-permeable scleral contact lens. METHODS: In this retrospective study, 14 eyes of 13 consecutive patients referred for the treatment of persistent corneal epithelial defects that failed to heal with conventional therapies or developed epithelial defects after penetrating keratoplasty for persistent corneal epithelial defects were fitted with an extended-wear gas-permeable scleral lens. These included seven eyes of six patients with Stevens-Johnson syndrome and seven eyes of seven patients who did not have Stevens-Johnson syndrome. Twelve eyes had undergone recent penetrating keratoplasty. All 14 eyes were fitted with a gas-permeable scleral contact lens designed to avoid the intrusion of air bubbles under its optic. An antibiotic and corticosteroid were added to the lens fluid reservoir or instilled before each lens insertion in 12 of 14 eyes. The lenses were worn continuously except for brief periods of removal for purposes of cleaning, replacement of the lens fluid reservoir, and examination and photography of the cornea. RESULTS: Five of the seven persistent corneal epithelial defects associated with Stevens-Johnson syndrome healed. The persistent corneal epithelial defects of four of these eyes re-epithelialized within 7 days, and a fifth healed in 27 days of gas-permeable scleral lens extended wear. A sixth persistent corneal epithelial defect that failed to heal initially re-epithelialized after a subsequent penetrating keratoplasty and gas-permeable scleral lens extended wear. The seventh eye healed after 3 days of gas-permeable scleral lens extended wear, but the persistent corneal epithelial defect subsequently recurred. Three of seven non–Stevens-Johnson syndrome persistent corneal epithelial defects re-epithelialized within 36 hours, 6 days, and 36 days, respectively. Of the six (six of 14) persistent corneal epithelial defects that failed to heal with a gas-permeable scleral lens extended wear, one subsequently healed after multiple amniotic membrane grafts. Microbial keratitis occurred in four eyes (four of 14) and graft failure in one eye, all of which required repeat penetrating keratoplasty. CONCLUSION: Extended wear of an appropriately designed gas-permeable scleral contact lens was effective in promoting the healing of persistent corneal epithelial defects in some eyes that failed to heal after other therapeutic measures. Re-epithelialization appears to be aided by a combination of oxygenation, moisture, and protection of the fragile epithelium afforded by the scleral lens. However, microbial keratitis represents a significant risk.

Ptosis prop gas permeable scleral lens fitting for a patient with ocular myopathy

This case report outlines the contact lens management of a patient with ocular myopathy who subsequently developed marked bilateral ptosis. The patient was successfully fitted with a pair of ptosis prop gas permeable scleral lenses.

Medical Applications of Scleral Contact Lenses

The indications and outcome of the wear of gas-permeable (GP) scleral contact lenses in 118 eyes of 85 patients attending a Scleral Contact Lens Clinic during a 5-year period from July 1988 to June 1993 were analysed. Ninety-nine eyes (83.9%) were originally fitted with PMMA lenses and were subsequently changed to GP lenses, whereas 19 (16.1%) were fitted with GP lenses from the outset. The mean duration of GP scleral lens wear was 15.3 months, with a range between 3 and 58 months. The indications for refitting the cases previously wearing PMMA scleral lenses with GP material were related to problems of chronic hypoxia. Thirty-three eyes (26.8%) had previous episodes of corneal oedema, and of the 27 that had a minimum of 3 months' follow-up, none experienced further episodes of oedema. Of the 32 eyes (26%) that had developed corneal vascularisation associated with PMMA scleral lens wear, two eyes were noted to have significant vessel regression after a period of GP wear, whereas in the remainder of cases, vessels remained static and nonprogressive. Thirty additional eyes (24.2%) experienced inadequate wear times associated with discomfort, and in these eyes the change to GP scleral lenses produced a statistically significant reduction in the inability to wear lenses beyond 4 h (p < 0.05).

Medical Applications of Scleral Contact Lenses

The medical indications for, and outcome of scleral contact lens wear in 517 eyes of 343 patients attending a Scleral Contact Lens Clinic during a 5-year period from July 1988 to June 1993 were analysed. Keratoconus was the most common condition requiring scleral lens wear (36.2%), followed by aphakia (18.4%), postpenetrating keratoplasty (12.0%), irregular astigmatism secondary to corneal disease (12.0%), high myopia (12.8%), and ocular surface disorders (6.4%). The main indication was visual (85.8%), whereas therapeutic indications accounted for 8.2% of cases. Seventy-six percent of cases had previously failed with other types of contact lenses. The majority of patients were initially fitted with impression moulded polymethylmethacrylate (PMMA) lenses (90.5%); other scleral lens types included preformed PMMA lenses, preformed high Dk gas-permeable (GP) lenses, and a GP/PMMA hybrid scleral lens design. Initial scleral lens fitting was successful in 93.2% of cases, and 71% remained successful with a mean duration of 11.8 years' follow-up. Complications included corneal vascularisation (13.3% of eyes), episodes of corneal oedema (7.4%), corneal abrasion (3.1%), and giant papillary conjunctivitis (1.7%). In addition to 19 eyes initially fitted with GP lenses, there were 99 eyes initially wearing PMMA lenses that were subsequently refitted with GP scleral lenses.

100+ Dk: does thickness make much difference?

Sealed impression scleral lenses were used to investigate if, with a material over MOM, reducing the lens thickness produced less adverse effects upon corneal metabolism. Three subjects wore sealed rigid gas permeable scleral lenses (115Dk) of different thicknesses. The central corneal thickness was measured pre- and post-wear. The results showed that the corneal swelling induced by the 0.30mm thick lens and the 0.15mm thick lens was not significantly different. Thus, when using a material with a permeability of over 100Dk, the centre thickness of the lens does not effect corneal metabolism as regards corneal swelling for lens substances below 0.30mm

A Gas-Permeable Scleral Contact Lens for Visual Rehabilitation

We evaluated the use of a highly gas-permeable, fluid-filled scleral lens for patients with diseased corneas for whom conventional contact lens strategies failed. Fifteen patients were successfully fit with individually fabricated scleral lenses. Significant corneal hypoxia, which limited the use of previous polymethylmethacrylate scleral lenses, was not encountered. Preliminary results suggest that a gas-permeable scleral lens may offer therapeutic as well as visual benefit to some patients with severe corneal disease.

The josef dallos award lecture 1989development of gas permeable scleral lenses produced from impressions of the eye

*Kenneth W. Pullum, BSc,FBCO,DCLP, t John H. Parker, BSc, ~Angela J. Hobley, PhD,MBCO,DCLP, lenses do not give an optimum result. They can be made according to specifications derived from preformed fitting sets or from eye impressions. Preformed fitting is awkward or impossible if the anterior ocular topography is irregular, when impression techniques are usually preferred. Both methods of fitting and the advantages and indications of scleral lenses have been described in many contact lens text books, most recently in Phillips and Stone, 1989. Dallos (1946) associated corneal hypoxia with Sattler's veil and this remains a major reason for scleral lens intolerance or reduced wearing time, often remaining intractable even afer repeated modification or refitting. It is an established clinical feature that corneal lenses made from RGP materials rather than polymethyl methacrylate (PMMA) improve comfort, wearing time and corneal metabolic state (Klyce et al 1985). RGP materials applied to scleral lenses could also provide a potential improvement, although it should be recognised that in order to avoid a high risk of breakage, the overall optic zone thickness of a thin scleral lens is nearly always thicker than even a thick high positive corneal lens. As a consequence, it would be expected that oxygen transmissibility through RGP scleral lenses should be less. Given buttons of sufficient size, there is no major difficulty involved in the production of RGP sclerals made to preformed specifications. This process was first described by Ezekiel (1983), and Ruben & Benjamin (1985) analysed the equivalent oxygen percentage (EOP) of preformed lenses made from the best RGP materials available at the time. Kok, (1988) described some therapeutic applications of RGP preformed scleral lenses. RGP materials are not readily available in sheet form, and even if they were their highly crosslinked nature precludes thermal moulding, therefore do not lend themselves to the traditional manufacturing process of impression lenses. Production of RGP impression sclerals by individually cast moulding the back surface and lathe cutting the front optic was described by Pullum (1987). Buck, (1988), reported success using a similar method but with different moulding substances. Sapp, Lyons et al, (1989), suggested an alternative method whereby an RGP button is glued into a PMMA scleral portion, with the back optic lathe cut to the closest approximation to the fitted PMMA lens.

Corneal response to gas-permeable impression scleral lenses

A scleral lens was successfully produced from a cast of an eye in a gas permeable material. By using a gas permeable material such as the Vistacryl GB, the level of central corneal swelling was significantly reduced (P<0.005) compared to the swelling induced by a PMMA scleral lens. The corneal swelling was similar for the gas permeable scleral lenses of thicknesses 0.50, 0.40, 0.30 and 0.18 mm.