Biometric Predictability in Combined Cataract Surgery and Ahmed Glaucoma Valve Implantation Depending on Tube Position

Anterior Segment Changes and Refractive Outcomes after Cataract Surgery Combined with Gonioscopy-Assisted Transluminal Trabeculotomy in Open-Angle Glaucoma

Objectives

To compare the accuracy of intraocular lens (IOL) calculation formulas in patients undergoing phacoemulsification combined with gonioscopy-assisted transluminal trabeculotomy (phaco-GATT) and to determine the predictive factors for refractive errors.

Materials and Methods

Fifty-three eyes of 53 patients undergoing phaco-GATT were retrospectively reviewed. The preoperative and postoperative 3-month anterior segment (AS) parameters were measured by Scheimpflug camera. The mean prediction error (PE), mean absolute error (MAE) in the Sanders-Retzlaff-Kraft/theoretical (SRK/T), Barrett- Universal II, Hill-radial basis function (Hill-RBF) and Kane formulas were compared. The influence of biometric parameters on PE were analyzed by correlation analysis.

Results

Postoperatively, there was a statistically significant decrease in axial length (AL) and significant enlargement in anterior chamber depth (ACD), anterior chamber angle (ACA), and anterior chamber volume (p<0.001). The mean PE using SRK/T (-0.08 diopters [D]) was more myopic than in the Barret (0.01 D) and Hill-RBF (0.01 D). The PE closest to zero was in the Kane formula (0.001 D). The Kane formula provided a lower MAE (0.30±0.28 D) than the SRK/T (0.38±0.32 D) and Barrett (0.36±0.30 D) (p<0.001). The MAE in Hill-RBF (0.32±0.28) was comparable with that in Kane (p=0.02). Preoperative AL was significantly associated with PE in all formulas except Kane. Barrett was the only formula that did not have a significant correlation between PE and postoperative ACD and ACA.

Conclusion

The Kane formula may provide higher predictability of the IOL power calculation than the SRK/T and Barrett-Universal II formulas in phaco-GATT surgery, which can cause significant changes in the AS and AL.

Risk of Refractive Prediction Error After Cataract Surgery in Patients with Thyroid Eye Disease

Purpose

To investigate the risk of unexpected refractive prediction error after cataract surgery in patients with thyroid eye disease (TED) at the University of Colorado.

Patients and Methods

A retrospective observational study was performed using records of patients who underwent cataract surgery (2014 to 2018) who were included in a Cataract Surgery Outcomes database. Any patient with documentation of thyroid eye disease (TED) in the medical record was classified as TED. Post-operative refraction error greater than or equal to ±1.0 diopter from the target refraction was the main outcome of this study. Eyes with history of refractive surgery, ocular trauma, retinal detachment, non-Graves’ disease thyroid conditions or Graves’ disease without TED, and eyes without refractive error at follow-up were excluded.

Results

A total of 5716 eyes from 3692 patients who underwent cataract surgery were analyzed. Sixty-five eyes of thirty-nine patients (1.1%) had TED. Former and/or current cigarette use was associated with having TED (p = 0.0504). Patients with TED had a statistically significant shorter axial length as compared to eyes without TED (p = 0.0257). Three hundred and forty-nine eyes (6.1%), including 9 eyes (13.8%) in patients with TED, had refractive prediction error greater than ±1.0 diopter following surgery (univariate OR = 2.5, 95% CI: 1.1–5.7, p = 0.0274). After multivariate analysis controlling for race, tobacco use, combined surgery, and axial length, TED was associated with an increased risk of our primary outcome, refractive prediction error greater than ±1.0 diopter (OR = 2.4, 95% CI: 1.0–5.7, p = 0.0506).

Conclusion

Patients with TED are at increased risk for refractive prediction error following cataract surgery. Discussion with patients regarding their risk and possible need for glasses following surgery is important for setting realistic patient expectations.