Optical Analysis and Reappraisal of the Peripheral Light Focusing Theory of Nasal Pterygia Formation

Impression Cytologic Evaluation of the Conjunctiva in Patients Treated with Topical 1% Voriconazole

Objectives

The aim of the present study was to evaluate any conjunctival metaplastic changes by impression cytology in patients who underwent topical 1% voriconazole treatment for severe fungal keratitis.

Materials and Methods

The study was conducted at Ege University Faculty of Medicine, Departments of Ophthalmology and Medical Pathology. Patients who were treated with 1% topical voriconazole for fungal keratitis for at least 3 months were included. The used topical voriconazole treatment was initiated as one drop every hour and was tapered according to clinical improvement in all patients. Treatment was continued 4 times a day for at least 3 months. Impression cytology samples were collected at least 3 months after cessation of topical voriconazole from the affected eyes and from the fellow eyes as a control group. Collected specimens were transferred to the pathology department for evaluation and grading (Nelson’s grading system).

Results

The mean age of the patients was 57.68±17.32 years (range, 22-87 years). The impression cytology grade of the inferior bulbar conjunctiva was 1.73±0.77 (range, 0-3) in the study group and 1.19±0.98 (range, 0-3) in the control group (p=0.03). The impression cytology grade of the temporal bulbar conjunctiva was 1.69±0.73 (range, 0-3) in the study group and 1.15±0.88 (range, 0-3) in the control group (p=0.02). The impression cytology grades of the nasal and superior bulbar conjunctiva did not differ statistically (p values 0.13 and 0.17, respectively).

Conclusion

Topical voriconazole is an effective broad-spectrum antifungal drug, but it induces conjunctival squamous metaplasia. Clinicians should be aware of this possible side effect of topical voriconazole and should carefully evaluate the conjunctiva of treated patients at each visit to detect possible metaplastic changes.

[Current possibilities for the diagnosis and treatment of pterygium]

Pterygium is a common inflammatory-proliferative disease characterized by the invasion of degeneratively altered fibrovascular tissue into the cornea. This literature review analyzes the etiological factors and pathogenetic concepts of its development, describes modern methods of diagnostics and surgical treatment of pterygium, and pays particular attention to the assessment of structural and functional changes in the cornea occurring during the growth of pterygium and after its excision.

Assessing and compensating for the confounding factors in Scheimpflug-based corneal densitometry

Scheimpflug-based corneal densitometry is a clinically verified method for assessing corneal transparency. Nevertheless, the estimates of corneal densitometry appear to be correlated with age and eye biometry parameters, such as the anterior chamber depth or the pupil size, and that ensues a convoluted conditional estimation problem, where it is difficult to interpret the results. This study aims at devising a methodology for compensating for such confounding factors by using, as a research platform, a commercially available Scheimpflug camera that allows exporting images in a dynamic fashion, allowing averaging the results from multiple acquisitions. Two approaches are considered, one based on appropriately normalizing the line densitometry signal and one based on image histogram equalization. Then, three parameters for describing corneal densitometry are derived including the mean value of backscatter and the scale and shape parameters of the Weibull distribution estimated in regions of interest encompassing parts of corneal stroma. The results show that, unlike the non-normalized measures, the proposed approaches lead to parameters that are not correlated with age nor the eye biometry.

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

Previous studies suggest that regions of corneal limbus may possess structural differences. We aimed to investigate the limbal changes associated with pterygium and aging via optical coherence tomography (OCT). Palisades of Vogt epithelial thickness (POV-ET) and Bowman’s membrane epithelial thickness (BM-ET) were measured at the nasal, temporal, superior, and inferior quadrants of patients with pterygium and healthy subjects of different ages. Values were expressed as a ratio that functioned as an index used to evaluate the change of limbus. Ratio values determined for quadrants of the corneal limbus were correlated highly in young healthy subjects. Further, parameter values were significantly greater than those of elder healthy subjects. In young subjects, the temporal and superior quadrants of patients with pterygium were significantly lower than those of healthy subjects. Temporal and superior quadrants of elder pterygium patients affected by both pterygium and age were significantly lower than those of healthy subjects; however, the inferior quadrant of elderly pterygium patients was significantly higher than that of age-matched healthy subjects. Our findings revealed that the thickness of limbal epithelium was negatively correlated with age, while pterygium led to the thinning of the temporal and superior limbal epithelium and inferior limbal epithelial thickening.