|Year : 2014 | Volume
| Issue : 2 | Page : 57-58
Old dogs, new tricks: Modern scleral contact lenses in refractory corneal
Department of Ophthalmology, China Medical University Hospital, Taichung, Taiwan
|Date of Web Publication||6-Jun-2014|
Department of Ophthalmology, China Medical University Hospital, Number 2, Yu- De Road, Taichung
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tsai YY. Old dogs, new tricks: Modern scleral contact lenses in refractory corneal. Taiwan J Ophthalmol 2014;4:57-8
The application of scleral lenses (SCL) began at the end of nineteenth century. Because of unacceptable wearing tolerance and the later development of soft contact lens, SCL were nearly obsolete for a long time. After undergoing improvements in lens design and corneal oxygenation, SCL nowadays have an important role in treating corneal disease. The characteristics that distinguish SCL from other conventional rigid gas-permeable (RGP) contact lenses are the larger lens size and fit feature. Scleral lenses bear on the sclera and vault over the cornea. Therefore, SCL can serve as a reservoir for the ocular surface and provide a smooth surface. The Scleral Lens Education Society (SLS) has recommended internationally recognized nomenclature for describing SCL according to thesizeand fit characteristics. The smallest lens size within this group is the semi-SCL (i.e., corneoscleral lenses), which typically ranges 12.0–15.0 mm in diameter; mini-SCL typically range 15.0–18.0 mm in diameter; and large SCL typically range 18.0–25.0 mm in diameter.
The indications for SCL are divided into 3 categories: (1) vision improvement in eyes with an irregular cornea, (2) ocular surface protection, and (3) cosmetic purposes. In the first category, corneal ectasia [e.g., keratoconus, pellucid marginal degeneration, kerato-globus, and post-laser-assisted in situ keratomileusis (LASIK) ectasia] is the primary indication for SCL fitting, followed by post-penetrating keratoplasty, and post-radial keratectomy (RK)., Compared to conventional RGP lenses, SCL afford sufficient vault over an excessively protruded or severely irregular corneal surface, and prevent recurrent corneal erosion caused by excessive cornea touch. Scleral lenses also offer more stable platforms for fine adjustment of their designs to improve visual quality. One large study reported a visual acuity of 9/6 or better in 78.7% of patients fitted with SCL for ectatic and post-surgical irregular corneas.
For the second purpose of SCL, patients with ocular surface disease benefited from the retention of fluid behind the SCL, which is believed to be a reservoir or a protector. Stevens–Johnson syndrome, graft versus host disease, ocular cicatricial pemphigoid, atopic keratoconjunctivitis, exposure keratitis, superior limbal keratoconjunctivitis, and neurotrophic ulcers are indications for SCL., Severe chemical and thermal injury contributing to limbal stem cell decificency and persistent corneal epithelial defect may also be considered indications. In one case series in which SCL were fitted for ocular surface disease, 92% of patients reported an improvement in their quality of life as a result of reduced photophobia and discomfort, and the mean wearing time was 13.7 hours per day, which is a good indicator of tolerance.
In the third category, painted SCL have been used for patients with aniridia and albinism. In addition to the cosmetic purpose, these patients also gain better visual quality because of reduced glare and photophobia.
In this issue, Hua-Lin Lo and associates report the clinical results of SCL for the visual rehabilitation of patients with keratoconus and irregular astigmatism. They fitted five keratoconus eyes and seven irregular cornea eyes post-refractive surgery (e.g., RK and LASIK) with 14.0–15.0 mm SCL. The mean best corrected visual acuity in logarithm of the minimum angle of resolution significantly improved from 0.71 ± 0.50 (range, 0.10–1.40) to 0. 05 ± 0.07 (range, 0.00–0.15) after SCL fitting. Another case report Chia-Chin Liao and associates demonstrate the use of mini-SCL for keratoconus and post-LASIK corneal ectasia in three patients. Their visual acuity improved to 20/50, 20/25, and 20/20. These two articles show successful SCL fitting without complications in eyes with keratoconus and corneal ectasia after refractive surgery, which may be refractory to RGP lenses. In addition to improving visual acuity, the tolerance of patients (e.g., daily wearing time and personal satisfaction) is the other crucial point for evaluating the results of SCL fitting.
In the near future, the application of SCL will be more extensive and special designs such as toric lenses and quadrant specific lenses will be more available for challenging corneal disorders. More information about SCL can be obtained from “A Guide to Scleral Lens Fitting”, which can be accessed at: http://artoptical.com/files/ documents/resources/Scleral_Lens_Fitting.pdf.
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