Unilateral superior pellucid marginal degeneration in a case with ichthyosis

Clinical profile and demographic distribution of pellucid marginal corneal degeneration in India: A study of 559 patients

Purpose:

The aim of this study was to describe the clinical profile and demographic distribution of pellucid marginal corneal degeneration (PMD) in patients presenting to a multitier ophthalmology hospital network in India.

Methods:

This cross-sectional hospital-based study included 2,470,793 new patients presenting between September 2012 and September 2020 (~8 years period). Patients with a clinical diagnosis of PMD in at least one eye were included as cases. The data were collected using an electronic medical record system.

Results:

Overall, 559 (0.02%) new patients were diagnosed with PMD. The prevalence rates were 0.004% in children (age <16 years) and 0.03% in adults. The majority of patients were males (70.13%) with the bilateral affliction (77.1%). The mean age of the patients was 37.91 ± 13.19 years. The majority (30.23%) of the patients were between 31 and 40 years of age. A significant number of patients were from higher socioeconomic status (93.74%) and from the urban region (45.08%). Of the 990 eyes, the most common clinical signs were ectasia/thinning (58.99%), corneal scar (17.47%), and corneal hydrops (1.01%). The majority of the eyes (87.97%) were managed with either spectacles or contact lenses. Among those who had surgical intervention, collagen cross-linking was the most performed procedure (5.25%) followed by cataract surgery (4.14%).

Conclusion:

PMD is a rare disease affecting patients seeking eye care in India. It commonly affects adult males and is bilateral in nature. The disease progression is slow and usually occurs beyond 3 years. Conservative management is more common than surgical intervention.

Corneal hysteresis and corneal resistance factor in pellucid marginal degeneration

Purpose

To evaluate and compare corneal hysteresis (CH) and corneal resistance factor (CRF) in pellucid marginal degeneration (PMD), keratoconus (KCN), and normal eyes using the Ocular Response Analyzer (ORA).

Methods

In this retrospective study, corneal biomechanical parameters were measured in patients with PMD (n = 102) and KCN (n = 202) and normal subjects (n = 208) using the ORA. Data, including full patient history as well as the results of refraction, slit-lamp biomicroscopy, Pentacam HR (Oculus), and ORA (Reichert; Buffalo, New York, USA), were collected from medical records. Also, the data of only one eye per individual were selected for the analysis. The inclusion criteria for PMD and KCN groups were a reliable diagnosis of these ectatic disorders based on the clinical and corneal tomographic findings. CH, CRF, CH–CRF, intraocular pressure (IOP) measurements were assessed for each subject. Data were analyzed with SPSS and MedCalc using the ANOVA, Pearson Correlation, and receiver operating characteristic (ROC) curve analysis.

Results

The mean CH was 8.91 mmHg ± 1.05 [standard deviation (SD)], 8.43 ± 0.78, and 10.89 ± 1.08 in the PMD, KCN, and normal group, respectively. Also, the mean CRF was 8.21 ± 1.35, 7.19 ± 1.11, and 10.69 ± 1.41 in the PMD, KCN, and normal group, respectively. ANOVA showed differences in the mean CH, CRF, and CH–CRF between three groups (P < 0.001). Also, ROC curve analysis showed the cut-off points ≤9.5, ≤9.5, and >1.3 mmHg for CH, CRF, and CH–CRF in the PMD group, respectively. For biomechanical parameters in PMD eyes, CRF had the highest sensitivity (75.49%) while the greatest area under the ROC curve (AUC) was seen for CH (0.903). Moreover, central corneal thickness (CCT) showed no correlation with CH (P = 0.30, r = −0.104) or CRF (P = 0.75, r = 0.033) in the PMD group.

Conclusions

This study presented the values of corneal biomechanics for PMD using the ORA. The results of the ORA were markedly different between PMD, KCN, and normal eyes.