Jay Won Rhim

Toric Intraocular Lens Calculations Using Ratio, of Anterior to Posterior Corneal Cylinder Power

PURPOSE To evaluate the accuracy of toric intraocular lens (IOL) calculation using estimated total corneal astigmatism based on the anterior-to-posterior corneal cylinder power ratio according to the axis orientation of anterior corneal astigmatism. DESIGN Retrospective cross-sectional study. METHODS Nine hundred twenty-eight eyes of 928 reference subjects and 20 cataract patients (20 eyes) implanted with a toric IOL were enrolled. Linear regression analysis parameters (β0 and β1) of relationship between the simulated keratometry cylinder (CylSimK) and posterior corneal cylinder power of reference subjects were used to calculate the estimated posterior corneal astigmatism (-[β1 × CylSimK + β0] @ 90). When regression analysis was not significant, estimated posterior corneal astigmatism was defined as the negative value of the mean posterior corneal cylinder power @ 90. Estimated total corneal astigmatism was defined as the vectorial sum of anterior corneal astigmatism and estimated posterior corneal astigmatism. Residual astigmatism error, predicted using SimK, was compared with that predicted using estimated total corneal astigmatism. RESULTS Estimated posterior corneal astigmatism was determined to be -(0.15 × CylSimK + 0.22) @ 90 in eyes with with-the-rule astigmatism, -(0.05 × CylSimK + 0.27) @ 90 in oblique astigmatism, and -0.27 @ 90 in against-the-rule astigmatism. The median magnitude of the predicted residual astigmatism error calculated using estimated total corneal astigmatism (0.30 cylinder diopters) was significantly smaller than that calculated with SimK (0.50 cylinder diopters). CONCLUSIONS Toric IOL calculations using estimated total corneal astigmatism based on the anterior-to-posterior corneal cylinder power ratio provided a more appropriate toric IOL cylinder power than calculations using SimK astigmatism.

A simple method to shorten the unfolding time of prehydrated hydrophobic intraocular lens

OBJECTIVE To evaluate the effect of warm ophthalmic viscosurgical devices (OVDs) on the unfolding time of prehydrated hydrophobic acrylic intraocular lenses (IOLs). DESIGN Experimental study and human trial. PARTICIPANTS Three foldable hydrophobic acrylic IOLs (enVista MX60, AcrySof SN60AT, and Tecnis 1 ZCB00). METHODS The unfolding times of 3 kinds of IOLs were measured according to temperature from 26°C to 32°C in a transparent container filled with a mixture of OVDs and balanced salt solution. The unfolding time of each IOL was measured 4 times for each temperature. Unfolding time was defined as the time required for the folded IOL to recover ≥ 90% of its overall optic diameter before folding. In human trials, the unfolding time of the MX60 in a capsular bag filled with 30°C OVDs was compared with that filled with room temperature OVDs for 4 cases in each group. RESULTS The unfolding time of the MX60 (215 ± 25 seconds) was significantly longer than that of the SN60AT (28 ± 7 seconds) and the ZCB00 (29 ± 7 seconds) at 26°C (p = 0.013). However, there were no differences in the unfolding time of 3 IOLs at 32°C. In human trials, the unfolding time of the MX60 was shorter in a capsular bag filled with 30°C OVDs (32 ± 13 seconds) than if filled with OVDs kept at room temperature (127 ± 27 seconds; p = 0.029). CONCLUSIONS When fast and complete unfolding characteristics are needed, filling the anterior chamber and capsular bag with OVDs warmed to 30°C before IOL implantation is recommended.

Risk factors for the development of transient hypotony after silicone oil removal.

Purpose: The purpose of the study was to determine the incidence, duration, and risk factors for postoperative transient hypotony after pars plana silicone oil removal. Methods: This was a retrospective, noncomparative, interventional case series. The records of 89 eyes of 89 patients who underwent pars plana silicone oil removal with at least 6 months of follow-up were reviewed. Postoperative transient hypotony was defined as an intraocular pressure of <6 mmHg occurring within 1 week of surgery, which recovered within 4 months after surgery. Results: Transient hypotony occurred in 35 of 89 eyes (39.3%). Thirty-three eyes recovered within 1 week after surgery. The logistic regression model, including age, number of previous pars plana vitrectomies, number of intraoperative endolaser applications, extent of remaining posterior proliferative vitreoretinopathy and the degree of proliferative vitreoretinopathy removal, number of preoperative antiglaucoma ophthalmic solutions, duration of postoperative anterior chamber inflammation, axial length, preoperative intraocular pressure, and duration of oil tamponade, showed that only axial length was significantly associated with the development of postoperative transient hypotony (odds ratio = 1.385, P = 0.023). Conclusion: Transient hypotony frequently developed after silicone oil removal, and most cases recovered within 1 week postoperatively. Patients with a long axial length had increased odds of developing transient hypotony after silicone oil removal.

Glistening Formation on a Single-Piece Prehydrated Hydrophobic Acrylic Intraocular Lens in a Diabetic Patient

PURPOSE To report a case of intraocular lens (IOL) glistening after uneventful cataract surgery and in-the-bag implantation of an enVista MX60 IOL (Bausch & Lomb, Rochester, NY) in a patient with uncontrolled diabetes mellitus. METHODS Case report. RESULTS A 76-year-old woman with non-insulin-dependent diabetes mellitus underwent uncomplicated phacoemulsification with in-the-bag implantation of an enVista MX60 IOL. After 6 months, glistening formation within the IOL optic was observed. In the fellow pseudophakic eye, an acrylic hydrophilic Akreos Adapt AO IOL (Bausch & Lomb) was implanted without complications. CONCLUSIONS IOL glistening can develop with the enVista MX60 IOL, even after uneventful cataract surgeries in certain situations (eg, uncontrolled diabetes mellitus). Increased vascular permeability due to uncontrolled diabetes mellitus might have been responsible for the postoperative IOL glistening formation. [J Refract Surg. 2016;32(10):710-712.].

Stratus OCT image analysis with spectral-domain OCT (Topcon 3D OCT Viewer)

Aims To assess the accuracy of the Topcon 3D OCT Viewer in analysing Stratus OCT data. Methods Randomly selected fast macular thickness map protocol optical coherence tomography (OCT) raw data were exported from the Stratus OCT database and imported into and analysed with the Topcon 3D OCT Viewer. The segmentation error (SE) rates and scores were compared between the two programs. Differences in the retinal thickness between the two programs were measured in both the SE (–) group and the SE (+) group. Results 356 eyes were analysed. The SE rate and mean SE score were significantly lower with the Topcon 3D OCT Viewer than with Stratus OCT ((30.9% (110/356) vs 38.2% (136/356), p=0.011; 0.33±0.59 vs 0.48±0.96, p=0.003), respectively). In the SE (–) group, the mean of the differences between the two programs was −2.79 μm (p<0.001) in the central 1 mm zone of the nine ETDRS areas and 1.49 μm (p=0.152) for the automated centre point thickness. Conclusions The Topcon 3D OCT Viewer analysed Stratus OCT data very well and displayed better segmentation performance. The Topcon 3D OCT Viewer program can be used interchangeably for the measurement of macular thickness, but careful interpretation by a clinician is needed.