Vogt striae: Demystified.

BACKGROUND

To study the correlation of different variables of Vogt striae to other attributes of keratoconus and to suggest a new grading system for Vogt striae to exactly represent the configuration and extent in each individual keratoconic cornea.

METHODS

The study was an observational and data review study. A total of 386 eyes of 207 keratoconus patients were screened from February 2016 to August 2018. Patients with prior history of collagen cross linking were excluded from the study as measurement of corneal thickness is less reliable for many months after collagen cross linking, and patients may have superficial corneal striae and scarring after collagen cross linking. Patients with history or clinical features suggestive of corneal hydrops or who had undergone lamellar or full thickness corneal transplants and intracorneal ring segments were also excluded from the study.

RESULTS

Of total 52 eyes with Vogt striae, 31 eyes (59.6%) had vertical orientation, 3 (5.8%) had horizontal, 11 (21.2%) had oblique while 7 eyes (13.5%) had mixed orientation of Vogt striae. Mean uncorrected distance visual acuity (UCVA) in the vertical group was 0.76 logMAR, horizontal group was 0.80 logMAR, oblique group was 0.65 logMAR, and mixed group was 1.17 logMAR units. Corneal scarring was present in 15 eyes (28.8%) and absent in 37 (71.2%) eyes with Vogt striae. In the mixed Vogt striae group, 85.7% eyes (6 eyes of 7) had corneal scarring, while 16.1% in vertical group (5 eyes of 31), and 27.3% in oblique group (3 of 11) had corneal scarring. Based on three attributes of Vogt striae, that is orientation, number, and corneal scarring, a new grading for Vogt striae was also suggested.

CONCLUSION

This is the first study to report the presence of mixed Vogt striae (combination of horizontal and/or vertical and/or oblique Vogt striae in a single cornea) in cases of keratoconus. For the first time, oblique Vogt striae have been described, and clear limits have been set to call it horizontal, oblique, or vertical striae. A new grading for Vogt striae is also suggested.