A Small step for Salzmann's
Lynette Johns OD FAAO FSLS
Salzmann’s nodular degeneration can be a challenging irregular corneal condition to fit with contact lenses. Patients may present with decreased best-corrected acuity but otherwise be asymptomatic - although symptoms may include photophobia, pain, irritation and dryness. Some nodules may also be vascularized. Vision can be improved with either a specialty soft contact lens or a form of gas permeable correction to mask the irregularity from the underlying nodules. Often, piggyback soft lenses are used to improve comfort for these patients. Scleral lenses can be an excellent contact lens modality for these patients to prevent corneal contact with the nodules.
Figure 1 (above) shows significant nasal corneal pannus in the left eye of a 46-year-old woman with a history of Salzmann’s nodular degeneration. She complained of constant irritation and photophobia in both eyes and was using preservative-free artificial tears every 1-2 hours. As an artist, she also complained of blurry vision. Without a contact lens, the light reflex on the corneal surface was very irregular. There were some vascularized and non-vascularized nodules with temporal paracentral haze. She has a history of surgical resection of pannus, but it recurred. The best spectacle-corrected visual acuity in this eye was 20/40.
Figure 2 (above) shows the right eye wearing a scleral lens. With scleral lenses she achieves 20/20 vision in each eye. The light reflex on the front surface of the lens is crisp and uniform, as the scleral lens front surface provides the irregular cornea with a smooth refractive surface while the preservative-free solution in the reservoir masks the irregularity from the nodules.
Figure 3 (to left) shows the significant elevation of the nodules with an optic section. These focal elevations pose a unique problem when fitting scleral lenses. The nodules in Salzmann’s nodular degeneration are often peripheral. Care should be taken to vault over these peripheral nodules. Corneo-scleral lenses may land, or bear, on the nodules and perhaps stimulate vascularization or advancing pannus. To bridge over the peripheral corneal nodules, large-diameter scleral lenses can provide increased peripheral and limbal clearance. Steepening the base curve will increase central clearance, but not necessarily limbal clearance. To avoid excessive central clearance, flat base curves can be employed with steeper peripheral curves to create a reverse geometry scleral lens.
Oblate scleral lenses can also create increased peripheral corneal clearance. Figure 4 (to left) shows peripheral corneal clearance.
Scleral lenses are a valuable tool when fitting patients who have Salzmann’s nodular degeneration. They have the ability to correct the irregular astigmatism while at the same time attenuating any dryness and irritation. Care should be taken with not only the peripheral clearance, but also with the scleral landing zone. Observe the landing zone carefully to make sure that the lens does not compress or impinge the vessels adjacent to the cornea, especially in cases of vascularized nodules and pannus. Optimizing the corneal clearance with balanced scleral and conjunctival alignment will provide patients with long-term wearing success.
Lynette Johns is an adjunct assistant professor and clinical attending in contact lenses at the New England College of Optometry.
She was formerly the senior optometrist at the Boston Foundation for Sight where she exclusively fit scleral lenses and managed complex corneal disease.
She is a fellow of the American Academy of Optometry and Scleral Lens Education Society as well as a member of the BCLA. She is a clinical and educational consultant to the GP and specialty soft lens division of Bausch + Lomb.