Combined Numerical And Structural Oct Staging Systems To Improve Full Course Management Of Keratoconus

Published 2024 - 42nd Congress of the ESCRS

Reference: PO803 | Type: Poster | DOI: 10.82333/7jbe-d386

Authors: Nanji Lu* ¹ , Iva Krolo ² , Silke Oellerich ² , Lele Cui ³ , Sorcha Ni Dhubhghaill ²

¹Ophthalmology,West China Hospital Sichuan University,Chengdu,China, ²Ophthalmology,University Hospital Brussels,Brussels,Belgium, ³Refractive Surgery Center,Wenzhou Medical University Eye Hospital,Wenzhou,China

Purpose

To compare two optical coherence tomography (OCT)-based keratoconus staging systems, namely the STEP numerical staging system and Sandali’s structural classification system, and to further integrate two staging systems.

Setting

Eye Hospital of Wenzhou Medical University

Methods

Scheimpflug tomography and spectral-domain OCT were performed on 300 eyes from 300 patients, with different stages of keratoconus. Two parameters from the STEP system, stroma overall minimum thickness (ST) and epithelium overall standard deviation (EP), were recorded to confirm the numerical stage information. Two independent reviewers evaluated all patients’ keratoconus structural stages based on Sandali’s system, and the structural classification was summarized. Two staging systems were compared and integrated to form a new comprehensive system.

Results

In Sandali’s system, 93.67% of eyes were classified as stage 1, of which 70.11% were above stage 1 using the STEP system. Stages ≥3 of Sandali’s system were all defined as stage 4 by the STEP system. The proposed comprehensive system categorizes stages 1 to 2 of Sandali’s system into stages 0 to 3 of the STEP system, and stages 3 to 5 into stage 4, respectively. The STEP system further divides stage 4 into stages 4a–4c to aid clinical decision-making by choosing corneal cross-linking, keratoplasty, or corneal implant procedures to improve visual function.

Conclusions

The two staging systems are not interchangeable; the STEP system is more suitable for detection and monitoring the early-stage keratoconus, while Sandali’s system might provide guidance with therapeutic choices for advanced-stage cases. The integration of these systems may enable a comprehensive management of eyes with keratoconus.