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Peripheral corneal relaxing incisions based on anterior keratometry from Scheimpflug tomography versus Placido
Mayank A Nanavaty1, Marizol Dizon2, Shruti Malde2
1Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, UK, BN2 5BF. mayank.nanavaty@bsuh.nhs.uk.
Aim:
To compare the outcomes of peripheral corneal relaxing incisions (PCRIs) based on standardized nomogram using keratometry from Scheimpflug and Placido machines during standard cataract surgery and to assess the astigmatism neutralization potential of PCRIs.
Methods:
In this prospective, comparative case series of eyes with keratometric astigmatism between 0.75D to 2.5D, undergoing routine cataract surgery, PCRIs were performed using standardized nomogram and keratometric data from either Scheimpflug or Placido machines. A single eye of 42 consecutive patients was recruited in each group. Data on pre- and postoperative uncorrected distance visual acuity (UDVA), corrected DVA (CDVA), keratometry and refraction were assessed at 10 weeks postoperatively. Refractive and keratometric J0 J45 vectors were also analyzed.
Results:
Data on 41 and 39 eyes were available in each group, respectively. There was a significant reduction in keratometric astigmatism in both groups. However, between Scheimpflug and Placido groups, there was no difference in postoperative logMAR UDVA [0.15 ± 0.18 vs 0.14 ± 0.16, p = 0.82] and CDVA [0.11 ± 0.11 vs 0.09 ± 0.10, p = 0.58], postoperative spherical equivalent [-0.34D ± 0.40D vs -0.50D ± 0.43D, p = 0.11], keratometric J0 [-0.03 ± 0.39 vs 0.01 ± 0.85, p = 0.67] and J45 [-0.03 ± 0.41 vs 0.01 ± 0.86, p = 0.65] and refractive J0 [0.05 ± 0.46 vs -0.03 ± 0.92, p = 0.47)] and J45 [-0.06 ± 0.49 vs -0.03 ± 0.99, p = 0.82] vectors, reduction of keratometric astigmatism [-0.40D ± 0.55D vs -0.35D ± 1.24D, p = 0.75] and the keratometric astigmatism neutralization potential [38.56 % ± 29.71 % vs 52.66 % ± 44.06 %, p = 0.12]. -
Conclusions:
Although PCRIs performed using Scheimpflug or Placido keratometry reduced the keratometric astigmatism significantly during standard cataract surgery. The astigmatic neutralization potentials of PCRIs comparing these two groups were not significantly different and remain low during the early postoperative period.
