Spheroidal Degeneration of the Cornea: Causes, Symptoms, and Treatment Options
Introduction
Table of Contents
Spheroidal degeneration of the cornea (SDC) is categorized into three forms: primary, secondary, and conjunctival types. The primary form occurs with aging in healthy eyes. The secondary form develops in eyes with existing conditions. The conjunctival type features deposits on the conjunctiva, sometimes affecting the cornea. SDC progresses in three stages. Stage 1 is peripheral, with no vision impact; Stage 2 involves the central area, reducing vision to 6/60; Stage 3 shows large golden droplets, severely affecting vision. Aging and UV exposure are significant risk factors, along with dry eyes, malnutrition, and trauma. Symptoms include foreign body sensation, pain, redness, photophobia, and poor vision, impacting the quality of life. This study examines SDC patterns and their links with other eye diseases at Menelik II Tertiary Referral Hospital.
Methods and Materials
Study Area and Period
A hospital-based prospective descriptive study was conducted at the anterior segment clinic (ASC) of Menelik II Tertiary Referral Hospital, Addis Ababa, from May 2021 to September 2022.
Source and Study Population
The source population included all patients with eye diseases visiting the hospital during the study. The study population focused on patients diagnosed with SDC.
Sample Size and Technique
All patients diagnosed with SDC during the study period were included.
Inclusion Criteria
All patients evaluated by the authors with an SDC diagnosis were included.
Data Collection
Primary data was gathered using a standardized tool covering relevant variables like age, sex, job type, visual acuity, and other eye conditions. All enrolled patients were assessed through a structured questionnaire and underwent comprehensive ocular examinations using a slit lamp biomicroscope. Visual acuity was measured with a Snellen chart, and intraocular pressure was assessed with an I-Care tonometer.
Diagnosis of SDC
SDC diagnosis was based on observing amber granules in the peripheral cornea and corneal opacification progression. SDC was categorized into three stages and types. When both eyes were affected, only one was recorded to avoid overestimation.
Data Analysis
Statistical analysis was performed using SPSS Version 26.0. Descriptive statistics were used to summarize study variables, and chi-square tests analyzed categorical variables.
Ethical Approval
Ethical approval was granted by the Research and Ethical Committee of the Ophthalmology Department at Addis Ababa University. Informed consent was obtained from all participants, following the principles of the Declaration of Helsinki.
Results
Sociodemographic Data
From May 2021 to September 2022, 24,068 patients visited the ASC, with 62 cases of SDC identified. Thus, the SDC prevalence rate was 0.258%. The gender distribution showed a higher prevalence in males (77.4%) compared to females (22.6%).
Outdoor and Indoor Activities
Ninety-one percent of respondents engaged in outdoor activities, while only 8.1% participated in indoor activities.
SDC Stages
Out of 62 cases, 15 (24.2%) were Stage I, 22 (35.5%) were Stage II, and 25 (40.3%) were Stage III. Types of SDC included 31 (50%) primary, 26 (40.9%) secondary, and 5 (8.1%) conjunctival.
Other Eye Diseases
Among SDC cases, 16.1% had posterior subcapsular cataracts, 16.1% had post-trachomatous corneal opacities, 12.9% had non-trachomatous corneal opacities, 9.7% had pterygium, and 4.8% had primary open-angle glaucoma. Sixteen (25.8%) cases showed no other eye disease.
Discussion
The study identified 62 SDC cases, which is lower than other studies (10.7% and 68.7%). This might be due to a short study period, with early-stage cases possibly not visiting a tertiary hospital.
Previous studies show varying prevalence rates in different regions. In this study, higher prevalence was noted in the 60-69 and 70-79 age groups. This differs from findings in Saudi Arabia, where younger age groups showed higher prevalence. Overall, the study found a higher prevalence in males and older adults, likely due to increased outdoor exposure.
Most participants (around 92%) had outdoor jobs, aligning with previous research suggesting outdoor workers, like fishermen, are more vulnerable to UV exposure.
The study found that Stage III cases were most common, with a significant proportion at Stage II and Stage I. Comparatively, other studies reported different stage distributions.
No significant associations were found between other eye diseases and SDC stage or type, contrasting with past findings showing links with cataracts and pterygium.
Limitations
- Study duration was short.
- It was a hospital-based study, not a community-wide survey.
- Mild cases might not have sought care at a tertiary hospital.
Conclusion
This study highlights the prevalence and characteristics of SDC in a specific population. Further community-wide research is needed to understand the broader implications of SDC and its associations with other eye diseases.