Lumps and bumps everywhere! When fitting scleral lenses, I have noticed more conjunctival abnormalities than ever before. These elevations may be a mild pinguecula or conjunctival cyst, or may be a more significant elevation such as a pterygium or status post glaucoma surgery including trabeculectomy, shunt, stent or glaucoma implant. The bumps may even be on the surface of the cornea such as in Salzmann’s nodular degeneration (Figure 1).
According to the Blue Mountains Eye Study of 3564 people aged 49 years or older, 266 subjects (7.3%) had pterygium (or a history of pterygium surgery) and 2521 (69.5%) had pinguecula present in either eye.1 Significantly more men than women had both pinguecula and pterygium. There were significant associations between pterygium and increased pigmentation (skin and hair color), decreased skin sun sensitivity and sun-related skin damage.1
In a study that examined the prevalence of pinguecula and pterygium in a general population in Spain of 1155 subjects age 40 years and older, the prevalence of pinguecula was 47.9% and increased significantly with age.2 The prevalence of pterygium was 5.9%; this also increased significantly with age. Of interest, after controlling for age and sex, pinguecula was strongly associated with alcohol intake.2
Figure 1. Corneal elevations in Salzmann’s nodular degeneration.
Corneal and conjunctival elevations may complicate the fitting of scleral lenses because a localized area may be elevated or uneven. In addition, intraocular pressure may be compromised if there is excessive pressure or rubbing over tube shunts or valves. This may lead to conjunctival and/or tube erosion, which can increase the risk of further complications such as endophthalmitis.
It is possible to fit inside of conjunctival abnormality by decreasing the lens diameter or to fit over the abnormality by increasing the lens diameter. Alternatively, it is possible to go around an elevation or abnormality with a scleral lens notch (Figure 2). Notching a scleral lens is quite straightforward. The first step is to measure the size (both length and width) of the conjunctival abnormality with a slit beam of the slit lamp or using scleral topography/profilometry. Next, measure the height and width of the conjunctival abnormality with the scleral lens on the eye. Then, mark the scleral lens with a sharpie or dry erase marker with the lens on the eye. (I like to inform the patient that I am marking the lens, not the eye). Then, measure the marking on the lens after the scleral lens is removed. Finally, call the laboratory consultant to discuss the plan and send the lens to the laboratory. Notching is performed manually and is not precisely reproducible.
Figure 2. Image of scleral lens notch.
When inserting the scleral lens with a notch, it is important to place it on the eye with the correct orientation. Be sure to inform the staff person who is training the patient on scleral lens application and removal—as well as the patient—about the need for proper lens orientation.
Another option offered by some manufacturers is a focal vaulting feature located at the edge or within the lens (Figure 3). A spherical elevation is created centrally inside the lens, and a hemispherical ripple is created at the lens landing zone, while still maintaining the circular shape of the lens edge. The focal feature vaults over a peripheral corneal or conjunctival elevation. The axis of the elevation relative to the center of the lens is first noted. Then, the distance from the center of the lens is determined by measuring the extent of the elevation from the edge. Finally, the width and depth of the central or peripheral vault feature is quantified.
Figure 3. Image of focal within the lens. Image courtesy of Brianna Ryff.
An advanced periphery design with impression based scleral lens technology such as an EyePrintPro (EyePrint Prosthetics) prosthetic scleral cover shell may also be used to avoid pressure on the conjunctiva and contact with the surgical area.
The next time you see a bump on the conjunctiva or cornea, consider scleral lens notching, focal vaulting, or impression based scleral lens technology.
1. Panchapakesan J, Hourihan F, Mitchell P. Prevalence of pterygium and pinguecula: the Blue Mountains Eye Study. Aust N Z J Ophthalmol. 1998 May;26 Suppl 1:S2-5.
2. Viso E, Gude F, Rodriguez-Ares MT. Prevalence of pinguecula and pterygium in a general population in Spain. Eye (Lond). 2011 Mar;25(3):350-7. doi: 10.1038/eye.2010.204. Epub 2010 Dec 24.
Dr. Melissa Barnett is a Principal Optometrist at the University of California Davis Eye Center in Sacramento, specializing in anterior segment disease and specialty contact lenses. Dr. Barnett is the Past President of The Scleral Lens Education Society. She lectures and publishes extensively on topics including dry eye, anterior segment disease, contact lenses and creating a healthy balance between work and home life for women in optometry.