Gas Permeable Scleral Contact Research Articles

Contact lenses for the treatment of ocular surface diseases.

Contact lens wear is useful in ocular conditions such as high refractive errors, irregular astigmatism, corneal ectasias, corneal dystrophies, post-keratoplasty, post-refractive surgeries, trauma, and ocular surface diseases. The new innovations of highly oxygen-permeable contact lens materials have broadened the applications of contact lens suitability. Therapeutic contact lenses are medically used in the management of a wide variety of corneal conditions and ocular surface diseases. These lenses aid in pain relief, enhance corneal healing, maintain ocular homeostasis, and act as a drug delivery system. Drug delivery applications of contact lenses hold promise for improving topical therapy. The modern rigid gas permeable scleral contact lens provides symptomatic relief in painful corneal diseases such as bullous keratopathy, corneal epithelial abrasions, and erosions. It has been useful in therapeutic management as well as visual rehabilitation by enhancing the ocular surface and protecting the cornea from adverse environmental conditions. This review provides a summary of contact lenses used for the treatment of ocular surface diseases based on the current evidence available in the literature. This can help enhance the understanding and management of ocular surface diseases with respect to contact lens use in our day-to-day ophthalmology practice.

Keratoconus: main lines of research

Keratoconus (KC) research focuses on studying pathogenesis, advancing diagnostic techniques and methods of correction and treatment. The working hypothesis for KC etiopathogenesis is based on abnormalities in distribution of microelements in the cornea and its potential influence on the processes of stromal collagen disorganization. Improvement of early diagnosis of KC is associated with evaluation of microstructural changes in the cornea using computerized methods such as Scheimpflug camera and high-definition optical methods for visualization of initial signs of a pigment ring. The main optimization directions of KC contact correction are associated with increasing gas permeability of the material, improving lens design and methods of lens fitting. Customized fitting of gas-permeable scleral hard contact lenses with consideration of topographic features of the anterior corneal surface allows achieving stable lens positioning and preserving the tear gap between the lens and the cornea. Alternative methods of correcting the refraction component of KC are associated with surgical interventions involving increase in corneal volume in the paracentral area. Implantation of corneal ring segments should be considered as an alternative to correction of refractive errors in cases with unsatisfactory individual subjective tolerance and insufficient patient compliance with contact correction. Femtolaser-assisted implantation of intrastromal allotransplants along with a decrease in the degree of spherical and astigmatic components of refractive errors contribute to prevention of KC progression. Advancement of techniques of corneal collagen cross-linking for prevention of KC progression is aimed at reducing the risk of developing post-operative complications directly related to the extent of intraoperative deepithelization. Limiting corneal ectatic area by implantation of intrastromal allotransplants can be considered an alternative approach. Deep anterior lamellar keratoplasty and penetrating keratoplasty are the surgeries of choice in replacing altered corneal layers in KC. With regard to the modern trends in selective keratoplasty, selective replacement of the cornea in lamellar keratoplasty reduces the rate of injuries and the risk of tissue reaction.

Tear Proteomic Approach and Identification of Tear Film Biomarkers with Rigid Gas Permeable Scleral Contact Lens (ScCLs) Wear for Keratoconus

Keratoconus (KC) is a classical non-inflammatory disorder associated with elevated serum levels of IgE, IgG, and IgM [1,2]. Lema et al. [3] have described specific cytokines and protease profiles in patients with keratoconus; and found levels of IL-6, TNF-alpha, and MMP-9 were elevated in keratoconus subjects as compared to normal. The differential expression of tear film proteins such as MMP-1, keratins, and mammaglobin B can be found in keratoconus subjects [4]. Tear fluid has been successfully used as a source of biomarkers in several well-studied eye diseases. Studies performed on tear fluid in patients of keratoconus provided insights into the pathology of the disease and revealed probable prognostic and diagnostic biomarkers for the disease [5]. A multi-omics approach integrating data from proteomics, lipidomics and metabolomics is the need of the hour for studying tear fluid as an important source of biomarkers in keratoconus to lead to effective prognosis and treatment of the disease. Tear fluid is a highly complex chemical and biological mixture containing proteins, peptides, electrolytes, lipids, and metabolites. It is proposed to be a surrogate representative for many eye diseases. It is an integral part of the ocular surface and represents the extracellular matrix for ocular surface epithelial cells [4,6]. Nano-mass Spectrometry and Liquid Chromatography were used in tear analysis, including analysis in proteomics, metabolomics, and lipidomics. Dry eye and meibomian gland dysfunction diseases involve the disruption of the lacrimal functional unit, resulting in symptoms of discomfort, visual disturbance, and tear film instability. These illnesses may exist independently as either symptomatic or asymptomatic disorders. However, they are frequently found in the same patient. The progression of these diseases typically leads to alterations in the tear film, tear hyperosmolarity, and the secretion of inflammatory mediators into the tears, initiated by cytokine release and metalloproteinase activation. Ocular dryness disorders also promote squamous metaplasia, mainly as a consequence of inflammation, whose severity can be used for grading different diseases affecting the ocular surface. In this study, we explored the efficacy of Rigid Gas Permeable Scleral Contact Lens in keratoconus regarding the expression of inflammatory Mediators.

Innovative Technologies To Improve Low Vision

According to WHO data from 2015 – globally 36 million people are blind, 253 million are visually impaired, 55% of whom are women. The creator of modern optical aids for the visually impaired is the famous American scientist William Feinbloom. The special devices to support the low vision are mainly divided into non-optical, optical and electronic. Of interest are the special magnifying devices for surgical implantation in the anterior segment of the eye – mini-telescopes. They apply the concept of enlarging the image on the retina, using a combination of minus and plus lenses as a magnifying glass. A new generation lens “Eyemax mono” is also a technological achievement. It is intended for monocular or binocular implantation in patients with AMD. An innovation is the use of a contact lens for visual rehabilitation – Contact Telescopic Lens. It is a solid gas-permeable scleral contact lens. The Argus II prosthesis is the first epiretinal prosthesis that restores vision in patients with Retinitis Pigmentosa. „Artificial intelligence“ glasses are too expensive. OrCam MyEye can read all printed texts, in addition, the device detects and recognizes objects and people, and recently has software in Bulgarian. In Bulgaria there is no integrated approach to the problem of the visually impaired. Most people with severe visual impairments, unlike complete blindness, have residual useful vision.

Therapeutic Contact Lenses in the Treatment of Corneal and Ocular Surface Diseases-A Review.

Therapeutic contact lenses (TCLs) are often used in the management of a wide variety of corneal and ocular surface diseases (OSDs). Indications of TCL include pain relief, enhancing corneal healing, corneal sealing, corneal protection, and drug delivery. For painful corneal diseases such as bullous keratopathy, epidermolysis bullosa, and epithelial abrasions/erosions, bandage contact lenses (BCLs) provide symptomatic relief. Postoperatively in photorefractive keratectomy or laser epithelial keratomileusis, BCLs also alleviate pain. In severe OSDs such as severe dry eye, Stevens-Johnson syndrome/toxic epidermal necrolysis, gas-permeable scleral contact lenses are often used to enhance corneal healing. BCLs are used post-keratoplasty, post-trabeculectomy, and post-amniotic membrane transplantation to enhance healing. BCLs, with or without glue adhesives, are used to seal small corneal perforations and sometimes also used as bridging treatment before penetrating keratoplasty in larger corneal perforations. In patients with eyelid conditions such as trichiasis, ptosis, and tarsal scarring, BCLs are also effective in forming a mechanical barrier to protect the cornea. A relatively new use for TCLs is in ocular drug delivery where TCLs are used to maintain therapeutic concentrations of medication on the ocular surface. Contraindications of the use of TCLs include infective keratitis, corneal anesthesia, and significant exposure keratopathy with inadequate eyelid position or movement. Complications of TCL include infective keratitis, corneal hypoxia and associated complications, corneal allergies and inflammation, and poor lens fit. Overall, TCLs are effective in the treatment of corneal and OSDs but contraindications and complications must be considered.

Ocular thermography in contact lens wearers

AbstractThe infra‐red thermal images have been used in the past for measuring the ocular surface temperature, its main advantage being the non‐invasive means. It is well‐known for its ability to detect the pathological and physiological changes in the eye.There are a few studies about ocular surface temperature and contact lenses. Some authors found that insignificant changes in ocular surface. temperature in soft contact lenses did occur, but other authors described that the pre‐lens tear film in soft lens wearers is cooler than that of the non‐CL‐wearing eye, while the temperature of the post‐lens tear film beneath the CL is higher. Regarding hard and gas permeable corneal contact lenses, the changes are between 0.5–1.5°C compared to the naked eyes. However, gas permeable scleral contact lens seems not to modify the ocular surface temperature despite the presence of the tear film stagnation under the lens.This presentation will navigate in the scientific literature about the usability and applicability of ocular thermography in contact lens wearers.

Optical Correction of Keratoconus with a Scleral Gas-Permeable Lenses

The optical properties of the cornea are determined by its ability to refract and transmit light. Keratoconus changes cornea’s shape, the surface of the cornea becomes irregular, which leads to a violation of light refraction and the occurrence of optical aberrations. The progressing course of the disease and its late detection lead to a delayed start of therapeutic measures, which affects the prognosis of the disease progression and reduces the patient’s quality of life. The quality of visual functions depends on the stage of the process. There are 4 stages of keratoconus (according to M. Asler), each of which corresponds to certain changes in refraction and degree of deformation of the cornea. Early biomicroscopic signs are: “dilution” of the stroma (inhomogeneity of the cornea and a grayish tint in the zone of the developing apex), change in the shape of endothelial cells and clearly visible nerve endings due to longitudinal thickening. In the second stage of keratoconus, the biomicroscopic picture is complemented by the appearance of keratoconus lines (Vogt’s striae). The opacities of the Bowman’s membrane indicate the beginning of the scarring process and the transition of the disease to its third stage. The fourth stage of the disease is characterized by further development of stromal opacities and the occurrence of gross changes of the Descemet’s membrane. Advanced medical equipment for topographic mapping and measuring the cornea makes it much easier for ophthalmologists to diagnose keratoconus and choose more effective treatment methods: crosslinking or surgical treatment. Later it allows to stabilize keratoconus, but does not provide high visual acuity due to the induction of optical aberrations, including high order optical aberrations. Contact lens vision correction is the main way to correct the refractive error resulting from keratoconus. However, the use of corneal gas permeable or soft contact lenses cannot provide high quality vision, additionally causing discomfort associated with their excessive mobility. The use of scleral gas permeable contact lenses is the most effective method of optical correction of all stages of keratoconus and after keratoplasty.

Scleral gas permeable contact lenses as a possible way of visual rehabilitation of patients with age-related macular degeneration

Low visual acuity, loss of the central visual field, metamorphopsia, distortion of lines and decreased contrast sensitivity cause reduced quality of vision in patients with age-related macular degeneration (AMD). Currently existing methods of visual rehabilitation for patients with AMD, such as telescopic intraocular and scleral lenses, are functionally and cosmetically unacceptable. The use of intraocular telescopic lenses is limited by the high risk of postoperative complications, low functional parameters, as well as by difficult ophthalmoscopy and lasting adaptation of patients. Telescopic scleral lenses have а low resolution, contain impermeable to oxygen parts and require wearing special switching glasses. However, scleral lenses have potential in developing an optimal method for vision correction in patients with AMD due to the presence of following advantages: wide optical zone, gas permeability, correction of refractive astigmatism in presbyopic patients and alleviation of dry eye symptoms. In conclusion, further clinical researches are required to develop a method for improving the quality of vision in patients with AMD by using scleral lenses with an objective test for evaluating the effectiveness of correction – the 3D computer-automated threshold Amsler grid test (3D-CTAG).

Visual rehabilitation of patients with irregular cornea

Purpose: To estimate the possibility of optical correction of an irregular surface of a cornea at primary ectasia (keratoconus) and secondary ectasia (a consequence of radial keratotomy (RKT) and Keratoplasty) for improvement of the maximum of visual acuity. Material and methods: In the study the scleral gas-permeable lenses (SGCL) were fitting by the 60 patients, it was 45 men and 15 women from them. The 46 patients had various stage of keratoconus and 14 patients had the keratectasia after RKT. On the 5 eyes of the patients was carried out keratoplasty earlier. Criteria of successful selection of SGCL considered achievement of steadily high visual acuity, comfort of carrying and the optimal clearance in apical zone, in the limbal and landing zone on the conjunctiva also. The results: In the course of the study, the maximum visual acuity in all patients was achieved with mini-SGKL correction irrespective of type of keratoektasia. All patients observed visual comfort compared with spectacle correction or correction with other types of contact lenses. Conclusion: Scleral gas-permeable contact lenses are the main method of correction at patients with irregular corneas and provide the best visual acuity.

Case series: Extended wear of rigid gas permeable scleral contact lenses for the treatment of persistent corneal epithelial defects

To report the successful treatment of persistent corneal epithelial defects that failed to respond to alternative treatment methods using extended wear of three different rigid gas-permeable scleral lenses. Eight eyes of eight patients with persistent corneal epithelial defects were treated with Blanchard Onefit 2.0 Scleral lens, BostonSight Scleral lens, and BostonSight PROSE device and were observed for defect resolution and improvement in best-corrected visual acuity over the duration of treatment. All eyes observed complete re-epithelialization with a mean time of 11.1 ± 5.5 days. At the conclusion of the treatment, visual acuity improved in all but one patient. No complications were observed during treatment. Scleral lenses provide the corneal epithelium with hydration, oxygen permeation, and protection from mechanical forces; thereby facilitating healing of persistent corneal epithelial defects. This case series demonstrates the successful use of continuous wear scleral lenses in a number of patients for the treatment of persistent epithelial defects refractory to other interventions.

Perry Rosenthal, M.D 1933–2018

Perry Rosenthal, M.D. passed away in Boston on March 3, 2018 at the age of 84. Remarkably, a number of his seminal contributions were made in the last two decades of his life and continued to evolve until his passing. He was born in Montreal, graduated from McGill University Medical School, and completed his residency in ophthalmology at the Massachusetts Eye and Ear Infirmary in Boston in 1963. Although a surgeon, he was fascinated by contact lenses and early in his residency founded the first contact lens service in the United States. Dr. Rosenthal established a private practice following his residency, specializing in contact lenses. He was particularly interested in rigid lenses and in 1971 co-founded Polymer Technology Corporation leading to the Boston rigid gas permeable material and the Boston lens. In 1986 he developed and fit the first fluid-ventilated gas-permeable scleral contact lens. It was at that early time that he was formulating concepts to explain the discomfort experienced by patients both with and without contact lenses, and came to believe that scleral lenses could play a large role in the treatment of those with ocular discomfort and pain. In 1992 he founded the nonprofit Boston Foundation for Sight. The Boston Foundation became the vehicle Dr. Rosenthal used to develop the Boston scleral lens (PROSE ocular prosthesis) which evolved into improved treatment for many conditions which had previously been untreatable; including the conditions of severe dry eye disease, Sjögren’s syndrome, chemical burns, neurotrophic keratitis, acoustic neuroma, severe keratoconus, marginal degenerations, and corneal scarring. Dr. Rosenthal was dedicated to providing this population suffering from significant ocular pain with improved comfort and vision and he achieved a level of success previously thought impossible. His work helped thousands of suffering patients throughout the United States and foreign countries. The PROSE lens was accepted by the professions as an effective treatment modality, and fitting centers to provide the PROSE lens and technology were established in cities in the US other than Boston and also internationally. Dr. Rosenthal was recognized for 8 consecutive years as one of the Best Doctors in the United States. I was fortunate to know Dr. Rosenthal for 40 years, as we were both in Boston and had many common interests. When our work converged in the area of ocular discomfort, a close friendship developed over the past 15 years, providing me with the opportunity to observe firsthand his passion for ocular pain, which truly dominated his waking hours. His work, including his publications, lectures and teaching, was responsible for providing those professionals who understood the extreme limitations of current therapy not only new directions in the management of dry eye, but in explaining why so many contemporary treatments failed for so many dry eye patients. However, for many years his work was ignored by many researchers and clinicians, as is the case with so many new ideas and new paradigms. At times Dr. Rosenthal expressed his frustration at the eye care professions unwillingness to consider his concepts which challenged conventional thinking. A continuing and ever growing number of researchers and clinicians have slowly embraced his concepts for ocular discomfort and pain, and as a result further research has been initiated. His contribution to the ocular pain system has changed my approach to the dry eye patient with pain. He received many awards and recognitions including: Best Doctors in America for 8 years from 2005–2012; 1997 Joseph Dallos Award; 2006 Howard Stein, Lecturer, Contact Lens Association of Ophthalmologists; 2007 Founders Award, American Academy of Optometry; 2007 UHCO Award for Distinguished Research on the Cornea and Contact Lenses; 2012 Dr. Donald R. Korb Award for Excellence; 2013 Harvard Medical School – Massachusetts Eye & Ear Infirmary Invited Speaker; and 2013 Keynote Speaker, Tear Film and Ocular Surface Society. In considering the contributions of Dr. Rosenthal, his work was truly pioneering in two areas. The first was the utilization of gas permeable scleral lenses for the treatment of previously untreatable conditions. This also resulted in the re-emergence of scleral lenses as essentially a new and important field of practice, not only for ocular discomfort and pain, but for a broad spectrum of visual conditions. The second area, and the focus of his work until his passing, is the ocular discomfort and pain system. Remarkably, each of these areas created new paradigms, resulting in Dr. Rosenthal being one of the very few in eye care who achieved multiple breakthroughs and paradigm shifts. With the passing of time, the wisdom and value of his visions and contributions become more apparent. He provided the foundation and guidelines for continuing research to carry his work to the next levels and provide readily implemented clinical methods to ameliorate the suffering of many. I am confident that history will view his contributions as seminal.

Irregular Corneas: Improve Visual Function With Scleral Contact Lenses

To assess visual function in patients with irregular cornea who do not tolerate gas permeable (GP) corneal contact lenses and are fitted with GP scleral contact lenses (Rose K2 XL). In this prospective study, we analyzed 15 eyes of 15 patients who did not tolerate GP corneal contact lenses and were fitted with scleral contact lenses (Rose K2 XL). We assessed visual function using visual acuity and the visual function index (VF-14); we used the VF-14 as an indicator of patient satisfaction. The measurements were taken with the optical correction used before and 1 month after the fitting of the Rose K2 XL contact lenses. We also recorded the number of hours lenses had been worn over the first month. Using Rose K2 XL contact lenses, visual acuity was 0.06±0.07 logMAR. In all cases, visual acuity had improved compared with the measurement before fitting the lenses (0.31±0.18 logMAR; P=0.001). VF-14 scores were 72.74±12.38 before fitting of the scleral lenses, and 89.31±10.87 after 1 month of lens use (P=0.003). Patients used these scleral lenses for 9.33±2.99 comfortable hours of wear. Both visual acuity and VF-14 may improve after fitting Rose K2 XL contact lenses in patients with irregular corneas. In addition, in our patients, these lenses can be worn for a longer period than GP corneal contact lenses.

Scleral contact lenses for visual rehabilitation in keratoconus and irregular astigmatism after refractive surgery

This study aims to report our experience of using fluid-ventilated, gas-permeable scleral contact lenses (SCLs) for visual rehabilitation of patients with keratoconus and irregular astigmatism after refractive surgery. This is a noncomparative interventional case series reporting eight consecutive patients fitted with SCLs because of irregular astigmatism following the failure of other optical corrections. Retrospective chart review and data analysis included age, sex, etiology prior to lens fitting, visual outcomes, follow-up time, and complications. Twelve eyes of eight patients were studied. All eyes were fitted with SCLs due to unsatisfactory vision with spectacle correction or other contact lens modalities. Five eyes had keratoconus and seven had irregular corneas post refractive surgery. The mean follow-up period was 14.4 ± 1.3 months (range 11–17 months). The mean age was 32.63 ± 7.68 years (range 18–48 years). The average steepest keratometry(Kmax) of our series was 49.56 ± 12.2 D. The mean refractive astigmatism was 5.50 ± 5.3 D. The mean best corrected visual acuity (BCVA) in logarithm of the minimum angle of resolution improved from 0.71 ± 0.50 (range 0.10–1.40) to 0.05 ± 0.07 (range 0.00–0.15) after SCL fitting (p < 0.001). All reported eyes achieved significant improvement in the BCVA with SCL fitting. None of the patients discontinued to wear SCLs. SCLs should be considered lenses of choice in irregular corneas refractory to conventional optical correction.

Microbial Keratitis Secondary to Unintended Poor Compliance With Scleral Gas-Permeable Contact Lenses

To report a case of neurotrophic keratitis in which scleral contact lenses improved vision from 20/100 to 20/20, however, due to poor lens care, an incident of microbial keratitis developed. A 64-year-old man with an ocular history of neurotrophic keratitis secondary to herpes simplex in each eye was successfully fit with scleral lenses. He subsequently developed microbial keratitis due to a number of risk factors. The lesion was culture negative, yet was very responsive to treatment with moxifloxacin. The lesion fully healed, and the patient did not suffer additional vision loss. This case demonstrates the ability of scleral lenses to correct visual impairments secondary to poor epithelial integrity and illustrates the importance of the practitioner providing detailed lens care instruction.

Scleral contact lenses for visual rehabilitation after penetrating keratoplasty: Long term outcomes

To evaluate the success rate of highly gas permeable scleral contact lenses (SCL) for visual rehabilitation after penetrating keratoplasty (PK), over a period of up to 9 years. A total database of 31 consecutive patient fitted with SCL between January 2004 and December 2009 was retrospectively reviewed. Demographic data, etiology prior to lens fitting, visual outcomes, follow up time and complications were analyzed. All eyes were fitted due to inadequate spectacle-corrected vision after successful penetrating keratoplasty or failure of other contact lens modalities. Out of 31 patients fitted, 28 (33 eyes) continue to wear SCL for periods between 0.5 and 8.8 years. The mean duration of follow-up after contact lens fitting was 5.2 ± 2.2 years. The mean age of corneal graft was 17.6 ± 11.4 years (range 4.3-42), and the mean interval between PK and initial contact lens fitting was 12.2 ± 10.7 years (range 0.7-36.0). The average steepest keratometry of our cohort was 55.0 ± 7.5 diopter (D) and the refractive astigmatism was 8.0 ± 4.4 D. The mean contact lens corrected visual acuity (BCVAcl) was 0.78 ± 0.25 (range 0.3-1.2). Twenty-three (82%) patients achieved a functional vision of 0.5 or more. During the studied period, ten (30.0%) eyes presented at least one graft rejection episode and two eyes (6%) had an episode of microbial keratitis. Corneal transplants of 20 years or more show a higher rate of refits due to ectasia recurrence. Scleral lenses should be considered as lens of choice in eyes with complex corneal geometry, as besides visual rehabilitation, their use may delay or prevent further surgical involvement.

Scleral Contact Lenses

Contact lenses are classified on the basis of the bearing zone area as Corneal, Corneo-scleral and Scleral lenses. Scleral lenses are large in diameter (18 - 23mm) and have a bearing completely on sclera. It has a large tear reservoir which helps in epithelial protection, enhances epithelial healing and enhances vision. Scleral lenses have evolved over the years in the material, design and fitting parameters. The earlier lenses were made of polymethacrylate, with poor oxygen permeability and caused corneal hypoxia. Later, came in the fenestrated scleral lenses. Although they had the advantage of minimal lens suction, they caused corneal exposure to air. The modern scleral contact lenses are made of material with high oxygen permeability and are non-fenestrated. These are called the rigid gas permeable scleral contact lenses. The scleral contact lenses are available in two types. They could be Preformed lenses or Impression technique designed. The Impression technique type, wherein a mold is prepared after impression, are no more in use. The Preformed scleral lenses come with a set of lenses with variable diameters and fitting parameters. Amongst the various parameters used in fitting of scleral contact lenses, the measurement of sagittal height is the most critical for a good fit. The sagittal height measurement has been made accurate with the advent of optical coherence tomography. The lens could be designed as spherical, toric or bifocal. Most common lens design used is spherical scleral contact lenses. Toric scleral lenses could be front toric, back toric or bitoric and used for patients with irregular astigmatism and corneal ectasia. Boston scleral lenses are one of the most popular scleral contact lenses. A highly customized lens for the patient is designed using the topographic guided software and gives the scope of changing lens fitting parameters instantly. The Boston scleral lenses find the maximum application on patients with end stage ocular surface disorders. The growing popularity of scleral contact lenses is due to the encouraging results in various indications. These can be broadly divided into indications for vision improvement (primary ectasia-includes conditions such as keratoconus, keratoglobus and pellucid marginal degeneration and the secondary ectasia group includes post-refractive surgery, including post-laser assisted in-situ keratomileusis, post-laser assisted epithelial keratoplasty, postphotorefractive keratectomy and postradial keratotomy) and indications for corneal protection (Steven Johnson syndrome, graft versus host disease, ocular cicatricial pemphigoid, neurotrophic corneal disease, atopic keratoconjunctivitis, Sjögren's syndrome, persistent epithelial corneal defects). It is important for every ophthalmologist to be aware of the option of treating patients with ocular surface disorders and corneal ectasia with scleral contact lenses. The article describes the various aspects of scleral contact lenses –classification, historical milestones in development, various modern scleral lens designs and fitting parameters. Published literature, indication and results of rigid gas permeable scleral contact lenses is also discussed.

Scleral Contact Lenses as an Alternative to Tarsorrhaphy for the Long-Term Management of Combined Exposure and Neurotrophic Keratopathy

Most ophthalmologists are unaware of the therapeutic applications of gas-permeable scleral contact lenses for the prevention and treatment of ocular complications in patients with facial nerve palsy and concomitant neuroparalysis. The case reports refer to 3 patients who developed unilateral lagophthalmos and corneal anesthesia after an acoustic neuroma or intracranial tumor resection. Two patients explicitly requested a tarsorrhaphy to be opened because they were incapacitated by the limited visual acuity and visual field. Tarsorrhaphy was not an acceptable aesthetic solution for the third patient. Fluid-ventilated scleral lenses were fitted because they protect the cornea by creating a precorneal fluid reservoir while optimizing visual acuity. The follow-up periods were 3, 17, and 18 years. Two patients wear the contact lenses full time, but the wearing time is limited to 10 hours per day for the third patient. All patients were instructed not to wear their lenses while sleeping. Two eyes required a corneal transplant, but lens wear could be resumed 4 to 6 weeks after transplantation. The learning curve for the insertion and removal of this large-diameter lens is the main obstacle for a patient, especially when there is loss of corneal sensation. Scleral lens wear is a valid long-term alternative to standard treatment options such as tarsorrhaphy for patients with corneal exposure and corneal anesthesia as a consequence of postsurgery facial nerve paralysis. Scleral contact lenses provide these patients with effective protection of the ocular surface in an aesthetically acceptable way while optimizing visual function.

Current applications and efficacy of scleral contact lenses — a retrospective study

Purpose To evaluate the indications and efficacy of high gas permeable scleral contact lenses (GP-SCL). Methods A total database of 97 consecutive patients (140 eyes) fitted with GP-SCL between January 2003 and December 2008, was retrospectively analyzed to determine the benefits of fitting scleral lenses. All lenses were fitted by preformed technique and were non-fenestrated. Patients included keratoconus – 88 eyes (63 %); corneal irregularities after penetrating keratoplasty – 39 eyes (28 %); various ocular surface disorders: Stevens-Johnson syndrome (SJS), graft versus host disease (GVHD) and exposure keratopathy – 6 eyes (4 %); post refractive surgery keratoectasia – 4 eyes (3 %), and high refractive error – 3 eyes (2 %). Results Mean follow up was 27.5 months (range 1–71), mean wearing time in successful wearers group was 12.2 hours per day (range 10–16), mean wearing time in group of wearers who dropped out using GP-SCL, was 5.8 hours (range 3–8). Keratoconus patients achieved median best corrected visual acuity (BCVA) of 20/32, 84 % of patients achieved BCVA of 20/40 or more. The post keratoplasty group achieved median BCVA of 20/25, 92 % of patients achieved BCVA of 20/40 or better. In the other groups, median BCVA was as follows: ocular surface disorders – 20/50, keratoectasia – 20/30, high refractive error – 20/32. Positive fluid-venting was highly associated with successful GP-SCL wearing. Twenty patients (21 %) failed to wear GP-SCL. Conclusions GP-SCL's expand the management of various corneal abnormalities. The main indication for GP-SCL is optical correction of an irregular corneal surface, especially keratoconus and corneal transplant.

Role of Rigid Gas-Permeable Scleral Contact Lenses in the Management of Advanced Atopic Keratoconjunctivitis

To describe the use of rigid gas-permeable scleral contact lenses (ScCL) in the treatment and visual rehabilitation of patients with medically controlled advanced atopic keratoconjunctivitis (AKC). Retrospective chart review of 10 eyes with medically controlled advanced AKC whose treatment included the use of ScCL for protection of the cornea from the ocular surface environment and visual rehabilitation. Outcomes measured were changes in biomicroscopic findings and visual acuity. Median follow-up period after ScCL fitting was 20.5 months (range, 14-32 months). An improvement in conjunctival hyperemia and corneal epithelial defects was observed in all eyes. Median best-corrected visual acuity before ScCL was logMAR 0.651 (Snellen 20/90; range, 20/45-20/400). After proper ScCL fitting, median logMAR visual acuity was 0.239 (Snellen 20/35; range, 20/20-20/50; P = 0.001). All patients gained at least 1 line of vision after initiation of ScCL, and 9 of 10 eyes experienced an improvement of at least 2 lines of vision. ScCL use was well tolerated by all patients, and no complications or infections occurred as a result of ScCL wear. Rigid gas-permeable ScCL are useful and safe to use in the management of the ocular surface and in the visual rehabilitation of eyes with medically controlled advanced AKC.

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.