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Contact lens exam reveals white corneal deposits
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A 62-year-old Hispanic man presented complaining of progressive deterioration in vision in both eyes with associated photophobia over the last 15 years. He expressed an interest in contact lenses as a form of vision correction because his glasses did not provide him with the required visual acuity necessary for driving a motor vehicle.
The patient reported having laser surgery in both eyes 10 years ago, which was later confirmed to be phototherapeutic keratectomy (PTK). He reported good visual acuity for 1 to 2 years postoperatively; however, subsequent deterioration ensued. Ocular history revealed a previous diagnosis of primary open angle glaucoma (POAG) in both eyes that was treated with latanoprost 0.005% ophthalmic drops every evening in both eyes. Family ocular history revealed that his mother suffered with POAG. The patient’s medical history was positive for hypertension, which was well controlled with 40 mg of lisinopril daily.
Best corrected visual acuity with spectacles was 20/100 OD with +3.50 D -1.00 D x 005 OD and 20/100 with +3.00 D -1.00 D x 060 OS with no improvement on pinhole. Neuro-ocular screening was normal. Anterior segment biomicroscopy revealed multiple discrete white stromal deposits only in the central 6.5 mm of the corneal stroma in both eyes. The corneal epithelium was clear and without staining with sodium fluorescein in both eyes, and his anterior chambers in both eyes were deep and quiet. His palpebral conjunctiva, lids, lashes and irises were clear and intact in both eyes. IOPs were 19 mm Hg OD and 17 mm Hg OS by Goldmann tonometry.
Further examination of his cornea with anterior segment OCT (Cirrus, Carl Zeiss Meditec) revealed hyper-reflective deposits throughout the central corneal stroma in both eyes. In the regions of stromal deposits, the underlying endothelium was irregular. The patient’s corneal topographies revealed irregular corneas with an oblate pattern in the left eye. Central pachymetry readings were 493 µm OD and 554 µm OS.
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Based on patient history, appearance and location of bilateral corneal stromal deposits, he was diagnosed with granular corneal dystrophy (GCD) type 1, also known as Groenouw type 1 corneal dystrophy.
GCD type 1 is an autosomal-dominant, bilateral, non-inflammatory corneal disorder. Musch and colleagues found that GCD type 1 was slightly more prevalent in women (62.3%) compared with men, and racial prevalence showed the highest in Caucasians (87.5%), followed by Hispanics (5.9%), with Asians and Blacks having the lowest prevalence (3.7%, 0.7%, respectively).
In GCD type 1, deposits that are well defined, gray-white in color and irregularly shaped are found in the central portion of the cornea below the level of the anterior to middle stroma. Intervening tissue and the peripheral 2 mm to 3 mm of the cornea adjacent to the limbus remain clear. The onset of these bread crumb-like deposits occurs during the first decade of life, with photophobia being the most commonly presenting initial symptom. Typically, by the end of the second decade, multiple deposits are seen, inducing a progressive reduction in visual acuity and increasing photophobia due to light scatter from the deposits. Although uncommon, recurrent corneal erosions can occur if the anterior corneal surface is affected.
Differential diagnoses
Thiel-Behnke corneal dystrophy presents with irregular, ill defined, subepithelial opacities in the central cornea at the level of Bowman’s layer in a honeycomb pattern that forms with time. Unlike GCD type 1, this condition does not exhibit clear intervals between the opacities.
Reis-Bücklers corneal dystrophy presents with gray-white, round polygonal opacities at the level of Bowman’s layer and superficial stroma, initially in the central cornea and extending to the limbus with time. Comparatively, the deposits in GCD type 1 have a lucid interval between them and the limbus.
Granular corneal dystrophy type 2 (also known as Avellino corneal dystrophy or combined granular-lattice corneal dystrophy) presents with amyloid and hyaline deposits in the anterior stroma. Granular deposits present first as small spots, eventually developing spokes resembling icicles. Lattice lines may also appear in the deep stroma. In the case of our patient, this dystrophy was ruled out due to the lack of lattice-like deposits within the cornea.
Macular corneal dystrophy (also known as Groenouw corneal dystrophy type 2) presents with diffuse stromal haze that extends to the limbus, with irregular deposits within the stroma and without lucid intervals between the deposits. This is not the case with our patient, because there were areas of clear cornea between the deposits in both eyes.
Genetic testing
An emerging diagnostic tool for patients with signs of a corneal dystrophy or with a positive family history is genetic testing. GCD type 1, GCD type 2, Reis-Bücklers, Thiel-Behnke, classic lattice type 1 corneal dystrophy and variants all have mutations on the TGFB1 gene located on chromosome 5q31. In-office buccal swab testing by Avellino Labs Inc. is now available on the market to aid in the diagnoses of these TGFB1 mutation dystrophies.
Genetic testing is now covered by insurance in a circumstance where signs are visible, as in our patient, or family history. Our patient denied a family history and preferred to not have genetic testing. However, his signs and symptoms point to GCD type 1.
Management of GCD type 1
Treatment in the early stages of GCD type 1 is not usually required because the visual acuity remains good. However, GCD type 1 can result in considerable deterioration in visual acuity and photophobia later in life. When this occurs, surgical intervention with PTK can be considered to improve visual acuity and decrease photophobia.
With PTK, an excimer laser ablates the granular deposits and smooths the corneal surface. Unfortunately, recurrence of deposits and an induced hyperopic shift can occur after PTK. Recurrence occurs in all patients, on average, 19.7 months after PTK therapy. Fifty percent to 70% of patients have a hyperopic shift after the procedure is completed (Namakara et al.).
Phototherapeutic refractive keratectomy (PTRK) is a newer technique being used to reduce the induced hyperopia post-PTK. PTRK is a combination of PTK and PRK and has been found to change the mean spherical equivalent power by +0.30 D ±1.00 D postsurgically.
Unfortunately, corneal irregularity can still be a refractive issue after PTK is performed, either due to the remaining deposits in the cornea after surgery or the recurrent deposits that will ensue over time. Our patient also had a thin cornea in the right eye, with pachymetry readings of 493 018 µm OD and 554 µm OS. Therefore, gas-permeable lenses are an excellent option to improve quality of vision in these cases.
Patient outcome
Due to the patient’s significant irregular corneal shape, scleral lenses were recommended over corneal GP lenses to provide the best vision. Despite the poor visual prognosis of GCD type 1, scleral lens correction offered not only a significant improvement in visual acuity but also quality of life. The patient achieved best corrected visual acuities of 20/60 OD, OS once fitted with X-Cel Specialty Contacts Atlantis scleral lenses in both eyes, with these parameters: OD: +1.50 D -2.25 D x 040, SAG 3.998 mm, base curve 7.67 mm, diameter 15.0 mm and center thickness 0.26 cm, and OS: +0.50 D -1.00 D x 095, SAG 3.998 mm, base curve 7.67 mm, diameter 15.0 mm and center thickness 0.26 cm. The material for both lenses was Optimum Extreme, which has a high Dk and a low wetting angle.
The patient was able to regain his independence, including recommencing driving, because driving standards in the State of Florida allow patients with no worse than 20/70 vision in either eye or both eyes together with or without corrective lenses to drive a motor vehicle. The patient also reported a decrease in photophobia, particularly feeling more comfortable in daylight and when driving at night.
Managing visual function of GCD type 1 can be challenging due to the poor visual prognosis, despite surgical intervention. Fortunately, scleral lenses were a viable visual rehabilitative option for success for our patient.
Editor’s note: This article has been updated to change this phrase: “… 20/70 or worse vision…” to this: “…no worse than 20/70 vision…”
- References:
- Chen M, et al. Ophthalmology. 2013;doi:10.1016/j.ophtha.2012.12.001.
- Kamiya K, et al. Sci Rep. 2016:doi:10.1038/srep24677.
- Kanski JJ, et al. Clinical Ophthalmology: A Systematic Approach, 8th ed., Elsevier; 2016
- Musch DC, et al. Invest Ophthalmol Vis Sci. 2011;doi:10.1167/iovs.11-7771.
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- For more information:
- Chandra Mickles, OD, MSc, FAAO, FSLS, is an associate professor at Nova Southeastern University College of Optometry. She is the coordinator of the university’s Dry Eye Care Center and teaches and publishes in the areas of contact lenses and ocular surface disease. She can be reached at: cmickles@nova.edu.
- Anisha Patel, OD, is a primary care and cornea and contact lens resident at Nova Southeastern University College of Optometry. She can be reached at: anishap8888@gmail.com.
- Joseph Sowka, OD, FAAO, Dipl, is professor of optometry at Nova Southeastern University College of Optometry.
- Edited by Leo P. Semes, OD, FAAO, a Primary Care Optometry News Editorial Board Member and Professor Emeritus in the Department of Optometry and Vision Science at the University of Alabama at Birmingham. He can be reached at: leopsemes@gmail.com.
Disclosures: Mickles, Patel and Semes report no relevant financial disclosures. Sowka reports he is co-owner of Optometric Education Consultants.