Keratoconus is an asymmetric noninflammatory progressive disorder that can present in different ways depending on the stage of the disease.1–3 At incipient stages (subclinical and forme fruste), the patient may be asymptomatic and the cornea may appear normal on slitlamp biomicroscopy. A diagnosis of keratoconus can be easily missed in such cases without the aid of corneal topography. Because most keratoconus cases present with irregular astigmatism and increase in myopia, it is even more challenging to detect keratoconus in hyperopia owing to the low level of clinical suspicion.2 This report highlights a rare case wherein a young high hyperopic man presented for refractive surgery was diagnosed to have bilateral keratoconus on corneal tomography without any clinical biomicroscopic signs.
A 29-year-old man presented for refractive surgery at the Centre for Sight, New Delhi, India, in January 2020. The corrected distance visual acuity (CDVA) was 20/25 in both eyes with a stable manifest refraction in the past 4 years. He had been wearing spectacles for the past 25 years with no history of contact lens use. No ocular surgery had been performed. His medical history and family medical history were unremarkable, having no systemic or ocular illness.
Slitlamp biomicroscopic examination showed normal findings in both eyes. Intraocular pressure and fundus examination were within normal limits. Topographic and tomographic examinations were performed using the Pentacam rotating Scheimpflug camera (Oculus Optikgeräte GmbH). Table 1 shows the clinical characteristics of the patient. The investigation revealed moderate astigmatism with greater inferior steepening in the right eye than in the left eye (Figures 1 and 2). Figures 3 and 4 show the topometric map in both eyes, indicating stage 2 keratoconus in the right eye and stage 1 to 2 keratoconus in the left eye. Figures 5 and 6 show the Belin/Ambrosio Enhanced Ectasia Display map in both eyes. The Corvis Tomographic and Biomechanical Index was 1.00 in both eyes. The corneal topographic and tomographic findings were suggestive of bilateral asymmetric keratoconus. Corneal crosslinking was not recommended because the patient had a stable refraction for the past 4 years. He was advised to repeat the Pentacam corneal tomography after 3 months. High Dk rigid gas-permeable (RGP) contact lens were prescribed, which provided a CDVA of 20/20 in both eyes.
Keratoconus is commonly presented with irregular astigmatism and myopia, leading to distortion of vision.2 However, presentation of keratoconus with high hyperopia and astigmatism is very rare.4–7 The present report analyses the case of a young man who presented with high hyperopia and astigmatism. The corneal tomographic pattern in both eyes showed inferior corneal steeping, corneal thinning, irregular astigmatism, and high anterior and posterior corneal abnormal elevation values suggestive of bilateral asymmetric keratoconus. Also, the Tomographic and Biomechanical Index was high in both eyes. One should raise suspicion of keratoconus in such cases of asymmetrical astigmatism, despite normal autorefractor keratometer readings.
Three cases of keratoconus with low hyperopic astigmatism were reported earlier by Abad et al.8 One of those cases was related to a posthyperopic laser in situ keratomileusis ectasia with a previous refraction of +1.00 diopter (D). The others presented with a simple hyperopic astigmatism (+1.25 D to +1.75D), with corneal topography suggestive of pellucid marginal degeneration (PMD) associated with keratoconus.8 Lee et al. studied 40 eyes with corneal ectatic disorders (PMD and keratoconus) and reported an 11% incidence of hyperopic astigmatism in 31 eyes with keratoconus or suspected keratoconus.9 The present case showed an uncommon association between keratoconus and high hyperopia (+10.00 D) with astigmatism.
In the literature, bilateral keratoconus associated with high hyperopia is reported as a rarely occurring entity, which may present with or without other ocular manifestations.4–7 Wagner et al. had demonstrated high hyperopia as a common finding in patients with Leber's congenital amaurosis.10 Sammouh et al. had demonstrated an association of hyperopic keratoconus with nanophthalmos, lipodermoids, and pigmentary retinopathy in a 44-year-old man in whom keratoconus was diagnosed on corneal topography.4 Bajracharya et al. had described a case of high hyperopia, keratoconus, and pigmentary retinopathy in which the diagnosis of keratoconus was made only when the child developed acute hydrops at the age of 10 years.5 Martin had reported a case of high hyperopia (+8.00 D) with bilateral keratoconus and PMD, with the presence of Vogt striae in 1 eye.6 Porcar et al. had described a case of high hyperopia (+8.00 D) and bilateral keratoconus, with the evidence of corneal thinning and Fleischer ring in 1 eye.7 The present report is an isolated case of bilateral keratoconus associated with high hyperopia and astigmatism without any clinical biomicroscopic findings or other ocular manifestations.
Management of stable keratoconus in mild-to-moderate cases is mainly accomplished with corneal RGP contact lens because of high levels of irregular astigmatism.11 RGP contact lens provide an effective option by masking corneal surface irregularities with the tear lens between the posterior contact lens surface and anterior corneal surface. Depending on the type of cone and its stage of progression, different contact lens fitting approaches may be required (materials and geometries). A combination of hydrogel lenses and RGP contact lens in a piggyback lens design can be used in later stages. In cases in which RGP contact lens are not well tolerated (excessive movement or decentered lens), then corneoscleral or scleral contact lens may be an appropriate option, which provide advantages (because of their large diameter in relation to RGP contact lens) such as excellent comfort, centration, stability, and an improvement in the quality of vision.12 A case report by Porcar et al. had described the management of bilateral keratoconus with high hyperopia (+8.00 D) and astigmatism using corneoscleral contact lens.7 We have advised corneal RGP contact lens in this case and the CDVA improved to 20/20 in both eyes. This is in comparison with the results of the case report by Martin in which he had fitted high Dk RGP contact lens with keratoconus design in a patient with bilateral hyperopic keratoconus.6
In conclusion, although rare, bilateral keratoconus may present with high hyperopia and astigmatism in the absence of clinical biomicroscopic findings. Management of stable hyperopic keratoconus using corneal RGP contact lens fitting may be similar to myopia-related keratoconus.
WHAT WAS KNOWN
- Keratoconus is characterized by corneal steepening and stromal thinning, leading to irregular astigmatism and myopia. Inferior paracentral corneal thinning is more common, but rarely superior thinning may also be seen.
WHAT THIS PAPER ADDS
- Bilateral keratoconus might rarely present with high hyperopia and astigmatism in the absence of clinical biomicroscopic findings.
- A high suspicion and corneal topography is recommended in all cases of asymmetrical astigmatism greater than or equal to 1.5 diopter between 2 eyes irrespective of the type of refractive error and normal autorefractor keratometer readings.
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