A novel nomogram for the treatment of astigmatism with femtosecond-laser arcuate incisions at the time of cataract surgery

Abstract

PurposeThe purpose of this study was to determine an arcuate incision (AI) nomogram to treat astigmatism during femtosecond laser-assisted cataract surgery.MethodsThis is a retrospective, cohort study. Femtosecond laser (FSL)-assisted transepithelial AIs were created at a 9.0 mm optical zone, 80% depth, centered on the limbus. We modified the manual Donnenfeld limbal relaxing incision nomogram to 70% for with-the-rule (WTR), 80% for oblique (OBL), and 100% for against-the-rule (ATR) astigmatism. The correction index (CI) equaled AI-induced astigmatism/target-induced astigmatism. Measures included preoperative keratometric corneal cylinder (Pre Kcyl), postoperative Kcyl (Post Kcyl), and postoperative residual refractive astigmatism (Post RRA).ResultsMean Pre Kcyl and 1–2 months Post RRA in 161 eyes of 116 patients were 0.626±0.417 diopters (D) (range 0.5–2 D), and 0.495±0.400 D (range 0–1.5 D), respectively. Mean absolute astigmatic changes (Pre Kcyl–Post Kcyl) without accounting for axis change in the WTR, ATR, and OBL groups were 0.165±0.383 D (P<0.001), 0.374±0.536 D (P<0.001), and 0.253±0.416 D (P=0.02), respectively. Mean absolute astigmatic changes using RRA as the postoperative measurement (Pre Kcyl–Post RRA) without accounting for axis change were 0.440±0.461 D (P<0.001), 0.238±0.571 D (P<0.05), 0.154±0.450 (P=0.111) in WTR, ATR, and OBL groups, respectively. CIs for WTR, ATR, and OBL were 0.53, 1.01, and 0.95, respectively. There were no intraoperative or postoperative complications related to the AIs.ConclusionTransepithelial FSL-AIs using the modified Donnenfeld nomogram show potential for management of mild to moderate corneal astigmatism. An increase in the magnitude or reduction of the optical zone size for the treatment of WTR and ATR astigmatism for this nomogram may further improve refractive accuracy.

<p>Astigmatic Outcomes of Single, Non-Paired Intrastromal Limbal Relaxing Incisions During Femtosecond Laser-Assisted Cataract Surgery Based on a Custom Nomogram</p>

“…Of the few studies that have investigated femtosecond laser AK or LRI efficacy, all reported their nomograms undercorrected. 7,20,21 Both Baharozian et al's anterior penetrating transepithelial LRIs and Day et al's paired intrastromal AKs significantly reduced corneal astigmatism, although their nomograms systematically undercorrected. 7,20 In Day et al's study, however, this was the intended outcome as they aimed to provide 70% astigmatism magnitude correction in order to avoid overcorrections.…”

“…7,20,21 Both Baharozian et al's anterior penetrating transepithelial LRIs and Day et al's paired intrastromal AKs significantly reduced corneal astigmatism, although their nomograms systematically undercorrected. 7,20 In Day et al's study, however, this was the intended outcome as they aimed to provide 70% astigmatism magnitude correction in order to avoid overcorrections. 7 Chan et al also found their personal nomogram of single, non-paired, femtosecond anterior penetrating AKs undercorrected overall, but overcorrections were seen when preoperative astigmatism <1.0D 21 a finding similar to the current study.…”

“…This follow-up was longer than other AK analyses reported in literature. 7,20,21 Lim et al found that keratometric astigmatism continued to change until 10 weeks, but then remained stable from 10-weeks to 3-years. 31 Therefore, the 3-month postoperative follow-up in the current study may have allowed for LRIs to stabilize, yielding more valid measurements over the long-term.…”

Assessment of surgeon experience with femtosecond laser-assisted cataract surgery

“…Recently published nomograms for both transepithelial and intrastromal arcuate incisions provide a useful starting point. 17 – 19 However, additional data and refinement of nomograms will improve predictability and outcomes.…”

<p>A Novel Sequential Docking Technique: Use of Femtosecond Arcuate Keratotomy and Femtosecond Assisted Cataract Surgery Using a Pupil Expansion Ring on a Patient with Intraoperative Floppy Iris Syndrome</p>

“…This technique obviates the insertion of a toric lens and can thus be considered a safer and more economical means for the correction of low-tomoderate corneal astigmatism. 15 The proximity of the Femto LDV Z8 to the patient's bed allowed us to employ a double-docking technique and conduct the procedure of FSAK and CCI separately from CCC and lens fragmentation. This two-step procedure, without any patient transfer, maximizes the benefits of FLACS.…”