Iop Changes With Non-Contact Tonometry (Nct) Versus Biomechanically Corrected Iop (Biop) And Incidence Of Subtle Steroid Response Following Smile For Myopia Correction

To evaluate intraocular pressure (IOP) changes and investigate the correlation of NCT and bIOP following SMILE for myopic correction and to identify cases of subtle steroid response

Nethradhama Super Speciality Eye Hospital, Bangalore, India

A total of 100 eyes of 100 patients, with mean age of 26 ± 3.2 years, who underwent SMILE for SE -1 to -10 D were included in the study. IOP was collected pre- and post- operatively by NCT (NT-510 – NIDEK, Tokyo, Japan) and bIOP (CORVIS-ST - Oculus, Wetzlar, Germany). Difference in both was evaluated before and after surgery on post op 2 weeks in all the groups. bIOP higher than 20 mm Hg was taken as cut off for steroid response.

The mean IOP (mmHg) by NCT, bIOP and their difference preoperatively was 15.81± 2.52, 16.48 ± 2.13 and 1.58 ± 1.55, respectively. At 2 weeks post-operatively, the mean IOP (mmHg) by NCT, bIOP and their difference was found to be 14.18 ± 2.64, 17.70 ± 3.16 and 3.16 ± 2.68, respectively. On analysis, 11 (11%) eyes were identified to have bIOP > 20 mmHg with apparently normal IOP by NCT. 21 (21%) eyes had bIOP values 5 mmHg higher than the corresponding NCT values.

Conventional methods of IOP estimation post corneal refractive surgery such as NCT may significantly under estimate post-operative IOP, thus masking cases of subtle steroid response. bIOP may be a more appropriate investigation in this scenario, as it accounts for the true changes in corneal biomechanics after refractive surgery, thus aiding in early identification and management of steroid responders.

 

Financial disclosure of all authors: Dr. Sri Ganesh and Dr. Sheetal Brar are consultants for Carl Zeiss Meditec