Corneal Topographic Patterns and factors associated with Keratoconus Among Patients Presenting with Ocular Allergy at a Tertiary Hospital in Northern Tanzania.

Abstract

Objective: To determine the corneal topographic patterns and factors associated with keratoconus among
patients presenting with ocular allergy.

Method: This was a hospital-based cross-sectional study conducted among patients aged 5–30 years with ocular
allergy. Data collection included questionnaires, slit-lamp examination, retinoscopy, and corneal topography.
Keratoconus was diagnosed using clinical signs and a steep K > 47.2D on topography. Topographic patterns
were also recorded. Data were analysed using STATA v17, with descriptive statistics and multivariable analysis;
p-values < 0.05 were considered statistically significant.
Results: A total of 270 participants (534 eyes) were enrolled, 61.9% of whom were male. Vernal keratoconjunctivitis
was present in 60.7% of participants. Keratoconus prevalence was higher via corneal topography (19.3%)
as compared to clinical signs alone (12.2%). Common topographic patterns among those with keratoconus
included inferior steepening (26.9%), round (21.2%), symmetric bowtie (13.5%), and asymmetric bowtie with
inferior steepening (13.5%). Significantly associated factors were aged >10 years (p = 0.001), allergy duration >5
years (p < 0.001), and chronic allergies: vernal keratoconjunctivitis and atopic keratoconjunctivitis (p < 0.001).
Conclusion: The prevalence of keratoconus is higher when diagnosed using topography compared to relying
only on clinical signs. This highlights the need for screening all patients with ocular allergy for keratoconus,
especially those with VKC and AKC, older age (>10 years) and longer duration of symptoms.