Cup and Disc Ratio and Inferior, Superior, Temporal and Nasal Calculation for Glaucoma Identification

Abstract

Glaucoma is the deadliest eye disease that steals the vision. Glaucoma is recorded as the second reason for vision loss. When identified it would have created 25% damage to the tissues and 50% vision loss. This has been so successful in stealing the vision because early detection of this eye disease is very difficult. This has catered the researchers. Early detection of glaucoma has always been challenging. In this paper, glaucoma is identified by checking two conditions namely Cup and Disc Ratio (CDR) and ISTN (Inferior, Superior, Temporal and Nasal) criterion. Both conditions must be satisfied to be glaucomatous. Vertical cup and disc diameter is obtained by Otsu threshold segmenting method. The cup to disc ratio is obtained by dividing the vertical disc to vertical cup diameter. ISTN is the criterion that ophthalmologist see to confirm glaucoma. The inferior region should have the greater thickness compared to other regions. A person is named a suspect of glaucoma if the CDR is above 0.6 and inferior region thickness is less than 8-pixel distance. Neural retinal rim thickness can also be taken for further validation.