Evaluation of ganglion cell complex thickness to total retinal thickness ratio for glaucoma using SD OCT

1. Yoshiyuki Kita¹
2. Ritsuko Kita¹
3. Seiji Takagi¹
4. Chiaki Nishimura²
5. Goji Tomita¹

¹Toho University Ohashi Medical Center, Tokyo, Japan
²Department of Medical Informatics, Toho University School of Medicine, Tokyo, Japan

Purpose: To evaluate ganglion cell complex (GCC) thickness to total retinal thickness ratio (G/T ratio) in normal and glaucomatous eyes using SD OCT.

Method: One hundred thirty-four eyes, divided into 3 groups: 27 eyes in the normal group, 74 eyes in the early glaucoma group, and 33 eyes in the advanced glaucoma group. SD OCT (RTVue-100) was used to measure macular total retinal, GCC, and outer retinal thickness. G/T ratio was calculated. The coefficient of variation (CV) value of GCC thickness and G/T ratio was also calculated.

Results: The mean±SD GCC for normal eyes was 97.6±8.5μm, 79.4±6.6μm for early glaucoma and 73.5±9.5μm for advanced glaucoma eyes, demonstrating a trend of decreasing GCC with increasing disease severity. The G/T ratio in normal eyes is 0.363±0.016, 0.318±0.017 in early stage, and 0.302±0.026, significant decrease in ratio was noted. The CV of GCC thickness and G/T ratio was as follows; GCC thickness in the order of normal, early group, and advanced group was 8.71％、8.30％, 12.88％ whereas, the G/T ratio was 4.49％, 5.31％, 8.64％, showing that the G/T ratio smaller in comparison.

Conclusion: Both GCC thickness and G/T ratio had decreased even in the early glaucoma. In addition, G/T ratio had smaller CV than GCC. The G/T ratio has potential for glaucoma diagnosis.