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A 66-year-old French-Canadian Caucasian man first presented to clinic for diabetic retinopathy screening in 2005. He was asymptomatic, with no ocular history of trauma, infection, or previous ocular surgery. His past medical history included type 2 diabetes mellitus and systemic hypertension. His prescribed drug intake included pravastatin, glyburide, nifedipine, and insulin. He had never consumed cigarettes or recreational drugs, and his alcohol consumption was occasional. There was no known family history of corneal dystrophies or degenerations. He denied any symptoms of photophobia, pain, cold sores, or fever blisters. He had previously worked in a bakery for 20 years before working as a car mechanic for the last 25 years. He denied any ocular chemical exposure during his career. The ocular examination revealed best-corrected visual acuities of 20/20 Snellen in each eye. Intraocular pressure was 12 and 13 mm Hg OD and OS, respectively. Slit-lamp examination revealed narrow grey-white full-thickness intrastromal corneal ring opacities in the mid-periphery bilaterally (Fig. 1). The appearance was symmetrical in both eyes. The bandwidth thickness was approximately 0.05 mm. The diameter was 7.1 mm in width and 6.5 mm in height OD and 6.9 mm in width and 6.2 mm in height OS. Corneal sensation was normal. There was no evidence of thinning, neovascularisation, or scarring. Some mild nuclear sclerotic lens changes and bilateral arcus senilis were noted, and the anterior chambers were quiet and deep. The dilated fundus examination was unremarkable.
The patient returned to the clinic in 2020 at the age of 82 years, referred for cataract evaluation. His ocular history at that time remained unremarkable. His medical history included recurrent cystitis and one episode of cutaneous herpes zoster, in addition to his diabetes, hypercholesterolemia, and systemic hypertension. His prescription drugs included rosuvastatin, metformin, glyburide, hydrochlorothiazide, nifedipine, enalapril, Asaphen (acetylsalicylic acid), and Novolin (human insulin). Ocular examination revealed the same symmetrical bilateral ring-shaped stromal opacities observed previously, with no progression since his initial presentation 15 years earlier. Nuclear cataracts were noted in each eye, with progression since his last visit. Keratometry readings were 42.24 and 42.78 D OD and 42.13 and 42.78 D OS. Axial length was 24.84 mm OD and 24.72 mm OS. His white to white was 11.8 mm OD and 12.0 mm OS. Corneal topography was not available.
Cross-sectional imaging of the cornea with anterior-segment optical coherence tomography revealed opacification with a grainy appearance affecting the entire thickness of the stroma (Fig. 2). The corneal epithelium and the endothelium appeared normal with no thinning or thickening. In 2020, the patient underwent a blood work-up. His hematologic and biochemical profile were unremarkable. His lipid profile was within the normal range with total cholesterol levels of 2.79 mmol/L, triglycerides of 1.18 mmol/L, low-density lipoprotein cholesterol of 1.22 mmol/L, and ratio of total cholesterol to high-density lipoprotein of 2.7. Of note, his high-density lipoprotein cholesterol levels were slightly below the normal range at 1.03 mmol/L. A urine analysis showed an abnormal presence of leukocytes, blood, and nitrites, likely secondary to his known recurring cystitis. His HbA1c was 6.7%, which is elevated. His thyroid profile was normal.
The patient underwent cataract surgery by phacoemulsification with posterior-chamber intraocular lens implantation in the bag in each eye, and both surgeries were uneventful. His final best-corrected visual acuity was 20/25 Snellen OD and 20/20 Snellen OS. To this day, the patient remains asymptomatic from the corneal opacities. The patient's direct family members were not available for examination.
First reported by Ascher in 1963, mid-peripheral corneal ring opacities are a rare finding. To our knowledge, they have been described in only 12 patients worldwide.
In all cases, a white opacity located in the mid-peripheral corneal stroma was observed with no central involvement. It was described bilaterally in all cases but 2, varying in both ring width and diameter in patients between the ages of 25 and 82 years. Common features of the opacity include a sharply demarcated round to slightly oval shape located in the mid-periphery, thin bandwidth, and diameters varying between 4 and 10 mm. Pachymetry, corneal health, and dilated fundus exams have been unremarkable. The overall appearance of the ring does not resemble any known corneal dystrophies or degenerations.
Our patient has full-thickness involvement of the cornea stroma similar to the patient of Nguyen et al.
While our patient was known for hypercholesterolemia, his blood lipid profile suggests good control of his cholesterol, low-density lipoprotein, and triglyceride on treatment. We noted the presence of concurrent arcus senilis on examination as well. Given his concurrent systemic illnesses of diabetes mellitus, hypertension, and dyslipidemia, a metabolic etiology could not be ruled out.
reviewed the different possible etiologies of these deposits, including topical or systemic drugs, ocular or systemic metabolic disorders, and corneal dystrophies or degenerations. The distribution of the opacities in a perfect symmetric ring suggests that the material was deposited after diffusion over a gradient between the peripheral and central cornea or vice versa. The sharp demarcation, absence of central stromal involvement, location in the mid-peripheral cornea, and stability over the years would argue against an immunologic reaction with stromal damage at the site of previous antigen–antibody interactions. Altered collagen fibril formation could account for the lack of any associated infiltrative or inflammatory response.
The lack of progression and target age group may suggest that the ring resulted from anomalous exogenous or endogenous extracellular microdeposits after exposition to an exogenous or endogenous factor for a defined period of time. At the present time, however, the etiology of this unusual finding remains unknown.
Footnotes and Disclosures
The authors have no proprietary or commercial interest in any materials discussed in this article.
Supported by: Nour Nofal: none; Mahshad Darvish-Zargar: advisory board, consultant, Alcon; consultant, research grant, Johnson & Johnson; advisory board, consultant, Allergan; advisory board, consultant, Novartis; and research grant, Bayer; Barbara Teboul, none.
Nour Nofal had full access to all data in the study, and he takes responsibility for the integrity of the data and accuracy of the data analysis. Patient informed consent was sought and obtained.
Corneal Ascher ring: a ring-shaped stromal corneal opacity.