Michael Goggin

Limbal relaxing incisions versus on-axis incisions to reduce corneal astigmatism at the time of cataract surgery.

PURPOSE: To compare limbal relaxing incisions (LRIs) with placement of the corneal cataract incision on the steepest keratometric axis for the reduction of preexisting corneal astigmatism at the time of cataract surgery. SETTING: The Queen Elizabeth Hospital, Adelaide, South Australia, Australia. METHODS: In a prospective single center study, patients having 1.5 diopters (D) or more of keratometric astigmatism were randomly assigned to 2 surgical techniques: on‐axis incisions (OAIs) consisting of a single clear corneal cataract incision centered on the steepest corneal meridian or LRIs consisting of 2 arcuate incisions straddling the steepest corneal meridian and a temporal clear corneal incision. Vector analysis of the target axis flattening effect was used to assess the efficacy of treatment. RESULTS: Seventy‐one eyes of 71 patients were evaluated, 33 in the OAI group and 38 in the LRI group. Six weeks postoperatively, the flattening effect was 0.41 D (median and interquartile range 0.15 to 0.78 D) in the OAI group and 1.21 D (range 0.43 to 2.25 D) in the LRI group (P = .002). After 6 months, the flattening effect was 0.35 D (range 0.00 to 0.96 D) and 1.10 D (range 0.25 to 1.79 D), respectively (P = .004). CONCLUSION: The amount of astigmatism reduction achieved at the intended meridian was significantly more favorable with the LRI technique, which remained consistent throughout the follow‐up period.

Comparison and reproducibility of corneal thickness and curvature readings obtained by the Galilei and the Orbscan II analysis systems

PURPOSE: To compare central corneal thickness (CCT) and keratometry readings using the Galilei dual Scheimpflug analyzer, the Orbscan II anterior segment analysis system, and the Sonogage ultrasound (US) pachymeter. SETTING: Lucerne Eye Clinic, Cantonal Hospital, Lucerne, Switzerland. METHODS: In a prospective single‐center study, 85 eyes of 45 healthy volunteers were examined with the Orbscan II and Galilei systems in random order followed by Sonogage US pachymetry. The CCT and keratometry measurements were compared using a paired t test. To assess the intraobserver and interobserver reproducibility of the 2 keratometers, 9 volunteers were examined 3 times by 4 independent observers and the intraclass correlation coefficient (ICC) was calculated. RESULTS: The mean CCT was 551.7 μm ± 36.6 (SD) with the Galilei, 554.8 ± 45.1 μm with the Orbscan II, and 558.5 ± 38.4 μm with the Sonogage. The CCT readings of the Galilei and Orbscan II did not differ significantly (P = .12). The mean keratometry readings with the Galilei and Orbscan II were similar, although both the steep (Ks) and flat (Kf) axes tended to be flatter with the Galilei system. The ICCs for CCT, Kf, and Ks were high with both keratometers (0.98, 0.97, 0.84 for Galilei and 0.97, 0.96, 0.95 for Orbscan II, respectively), indicating that variation in measurements was mainly due to true subject‐to‐subject variation rather than observer error. CONCLUSION: Keratometry and pachymetry readings with the Galilei and Orbscan II systems showed good concordance and high reproducibility, which would allow the examinations to be delegated to nonmedical personnel.

Refractive outcome following diode laser versus cryotherapy for eyes with retinopathy of prematurity.

The refractive error in 15 eyes with threshold retinopathy of prematurity treated with diode laser photocoagulation was compared with 25 eyes with the same disease severity treated by cryotherapy. Myopia was present in 40% (six eyes) of the first group ranging from -1.50 to -3.50 dioptres; while 92% (23 eyes) showed myopia which ranged from -0.50 to -8.00 dioptres in the cryotherapy group. Sixty per cent (nine eyes) were hypermetropic at less than +3.0 dioptres in the laser group, while only 8% (two eyes) of the cryotherapy group showed hypermetropia. There was no significant difference in astigmatism between the two groups. Eyes with threshold disease treated with diode laser photocoagulation developed significantly less myopia than those treated with cryotherapy (p = 0.0006, two tailed value).

Toric Intraocular Lens Outcome Using the Manufacturer's Prediction of Corneal Plane Equivalent Intraocular Lens Cylinder Power

OBJECTIVES To describe the refractive outcome of toric intraocular lens (IOL) implantation by comparing the postoperative refractive astigmatism with the preoperative keratometric astigmatism target. METHOD In a university department of a publicly funded hospital, 38 eyes of 29 patients underwent routine cataract surgery with insertion of a toric implant (SN60TT AcrySof Toric). Surgically induced astigmatism was derived using vector analysis of refractive outcome vs predicted postoperative keratometric astigmatism and compared with the targeted induced astigmatism. RESULTS Postoperative remaining refractive astigmatism of 0.97 diopters (D) was achieved vs a target of 0.61 D. A mean (SD) surgically induced astigmatism value of 1.78 (0.89) D was derived compared with a mean (SD) targeted induced astigmatism value of 1.58 (0.47) D (calculated by the manufacturers online calculator, which predicts IOL corneal plane equivalent cylinder power and postoperative keratometric cylinder). CONCLUSIONS Toric IOLs are a safe, predictable method of astigmatic correction. However, some remaining astigmatism is commonly present owing to the necessary nonzero astigmatic targets imposed by the steps between IOL cylinder powers, variability of axis, and power effects of surgical incisions as well as by underestimation of the corneal plane cylinder power of the IOLs by the manufacturer.

Outcome of Toric Intraocular Lens Implantation After Adjusting for Anterior Chamber Depth and Intraocular Lens Sphere Equivalent Power Effects

OBJECTIVE To describe the refractive outcome of toric intraocular lens (IOL) implantation by taking into account the effect on astigmatic outcome of the anterior chamber depth and the sphere power of the IOL, and to examine whether the predictability of the toric effect can be improved. METHOD In a university department in a publicly funded hospital, 38 eyes of 29 patients underwent routine cataract surgery with insertion of a toric implant (SN60TT AcrySof Toric). The corneal plane effective cylinder power of the IOL was calculated, including the effect on this value of the anterior chamber depth and pachymetry and of the sphere power of the IOL. RESULTS The mean (SD) corneal plane equivalent cylinder power of the IOL predicted preoperatively by the manufacturer as 1.58 (0.47) diopters (D) vs 2.02 (0.64) D by us (calculated using predicted postoperative anterior chamber depth and IOL sphere values). The mean (SD) measured postoperative value was 1.78 (0.89) D, which was better predicted by us. CONCLUSIONS The manufacturer currently appears to underestimate the corneal plane effective cylinder power of its toric IOLs. Improved outcome could be achieved by estimating the effective corneal plane cylinder power of the IOL, as altered by the anterior chamber depth and pachymetry and by the IOL sphere power, but this is currently not addressed by the manufacturer.

Diode laser photocoagulation to the vascular retina for progressively advancing retinopathy of prematurity.

AIMS--To estimate the effectiveness of diode laser photocoagulation of the retina posterior to the ridge in eyes with retinopathy of prematurity (ROP). METHODS--Diode laser photocoagulation was applied posterior to the fibrovascular ridge in stage 4a ROP in six eyes of four infants and in advancing stage 3+ in two eyes of one infant. Seven eyes had previously been unsuccessfully treated with diode laser photocoagulation anterior to the ridge. RESULTS--Six eyes of four children had total regression, two eyes of two children had flat maculae with residual peripheral tractional detachment and maintained vision. CONCLUSION--These preliminary results indicate that diode laser photocoagulation posterior to the ridge may be a useful treatment in late stage 3 and stage 4A ROP following failed laser treatment to the avascular retina in threshold stage 3 disease.

Comparison of refractive outcomes using immersion ultrasound biometry and IOLMaster biometry

Background:  The IOLMaster determines axial length using partial coherence interferometry. This study was designed to compare the refractive outcomes of patients who had been measured preoperatively by both immersion ultrasound and IOLMaster biometry.

Variation in surgically induced astigmatism estimation due to test-to-test variations in keratometry.

Keratometric, videokeratoscopic, or refractive surgically induced astigmatism (SIA) is a calculation of surgical change in astigmatic values. Test-to-test variation occurs in keratometry, and a keratometryderived SIA-like value can be derived from one test to the next without surgical intervention. The term surgically induced astigmatism would be inappropriate so we have termed this vector value astigmatism measurement variability. We performed a study to examine the astigmatism measurement variability in 4 keratometric devicesdNidek ARK510A, Humphrey ARK599, IOLMaster V3.02 (Carl Zeiss Meditec AG), and Pentacam HR7900 (Oculus, Inc.)dto determine the most reliable device, the astigmatism measurement variability of each device, and which device produced the least bias. Sixteen volunteer subjects (32 eyes) had 2 bilateral keratometrymeasurements by the 4 devices. Intraclass correlation coefficients (ICCs) were calculated for each device for flattest (Flat K) and steepest (Steep K) keratometric measurements and the meridian of the Steep K for each eye. These were all greater than or equal to 0.93 except the Pentacam steep meridian measurement, which was 0.85. Although the IOLMaster had the highest reliability for Flat K (ICC 0.989) and Steep K (ICC 0.990), its reliability dropped for Steep K meridian (ICC 0.944). The Nidek device had a high ICC for all 3 measurements (Flat K, 0.960; Steep K, 0.979; and Steep K meridian, 0.989). A coefficient of variation was calculated for each device (Table 1), and the Nidek device was the most precise. Astigmatism measurement variability values (magnitude and axis) were calculated for each eye using each device (Table 2) and were similar for the Nidek, Humphrey, and IOLMaster. The Pentacam produced a significantly larger value (P Z .0146). Furthermore, the summated vector means of the astigmatism measurement variability were derived as a measure of systematic error. The values were as follows: Nidek, 0.03 diopters (D) 41 degrees; Humphrey, 0.08 D 12 degrees; Pentacam, 0.14 D 115 degrees; IOLMaster, 0.10 D 142 degrees; and for all 4 devices combined, 0.03 D 136 degrees. Although the values for all the devices were small, those of the Pentacam and IOLMaster were an order of magnitude larger than those of the Nidek or Humphrey; the Nidek has the lowest value.

Awareness of and compliance with recommended dietary supplement among age-related macular degeneration patients

Background:  The age‐related eye disease study suggested that taking zinc and anti‐oxidants supplements could reduce the progression of age‐related macular degeneration (AMD). In Australia, the available supplement is Macu‐Vision. The study aimed to assess the awareness of and compliance with taking this supplement and the public health implication.

Astigmatic neutrality in biaxial microincision cataract surgery.

PURPOSE: To assess the astigmatic effect of biaxial microincision cataract surgery (MICS) with insertion of an UltraChoice 1.0 Rollable Thinlens intraocular lens (IOL) in a sufficiently powered controlled study. SETTING: Queen Elizabeth Hospital, South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, Australia. METHODS: Consecutive patients having biaxial MICS were evaluated prospectively. Keratometry was performed preoperatively and postoperatively. Vector analysis of the alteration in the keratometric cylinder was compared with that in control eyes not having surgery but having keratometry over a similar time frame. RESULTS: There were 76 eyes in the surgical group and 74 in the control group. The right‐hand incision used for IOL insertion had a mean external opening width of 2.00 mm and a mean internal width of 1.89 mm. The left‐hand incision measured a mean of 1.49 mm and 1.46 mm, respectively. There was no statistically significant difference between the surgical group and the routine variability in keratometry in the untreated control group in surgically induced astigmatism (surgical group, 0.57 diopter [D] ± 0.05 [SEM]; control group, 0.54 ± 0.06 D; P =.660) or the degree of mean calculated flattening effect at the right‐hand incision (0.01 ± 0.06 D and −0.05 ± 0.05 D, respectively; P = .405) or at the left‐hand incision (−0.06 ± 0.05 D and 0.03 ± 0.06 D, respectively; P = .283). CONCLUSION: Biaxial MICS with insertion of IOL through a temporal incision of 2.0 mm offers prospects of astigmatic neutrality in cataract surgery.