Intraocular lens power calculation using adjusted corneal power in eyes with prior myopic laser vision correction.

PURPOSE: To evaluate the prediction accuracy of the intraocular lens (IOL) power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio in the Haigis formula (Haigis-E) in patients with a history of prior myopic laser vision correction. METHODS: Seventy eyes from 70 cataract patients who underwent cataract surgery and had a history of myopic laser vision correction were enrolled. The adjusted corneal power obtained with conventional keratometry (K) was calculated using the posterior/anterior corneal curvature radii ratio measured by a single Scheimpflug camera. In eyes longer than 25.0 mm, half of the Wang-Koch (WK) adjustment was applied. The median absolute error (MedAE) and the percentage of eyes that achieved a postoperative refractive prediction error within ± 0.50 diopters (D) based on the Haigis-E method was compared with those in the Shammas, Haigis-L, and Barrett True-K no-history methods. RESULTS: The MedAE predicted using the Haigis-E (0.33 D) was significantly smaller than that obtained using the Shammas (0.44 D), Haigis-L (0.43 D), and Barrett True-K (0.44 D) methods (P < 0.001, P = 0.001, and P = 0.014, respectively). The percentage of eyes within ± 0.50 D of refractive prediction error using the Haigis-E (78.6%) was significantly greater than that produced using the Shammas (57.1%), Haigis-L (58.6%), and Barrett True-K (61.4%) methods (P = 0.025). CONCLUSION: IOL power calculation using the adjusted corneal power according to the posterior/anterior corneal curvature radii ratio and modified WK adjustment in the Haigis formula could improve the refraction prediction accuracy after cataract surgery in eyes with prior myopic laser vision correction.

Rainbow halos occur less following implantation of extended range of vision one-piece intraocular lenses vs diffractive bifocal intraocular lenses.

AIM: To evaluate clinical outcomes following implantation of an extended range of vision intraocular lens (IOL), the ZXR00, and a diffractive multifocal IOL with +2.75 diopters (D) add power, the ZKB00. METHODS: Totally 30 patients who underwent either bilateral implantation of the ZXR00 IOL with intended emmetropia (ZXR00 emmetropia group: 20 eyes) and intended micromonovision (ZXR00 monovision group: 20 eyes), or bilateral implantation of the ZKB00 IOL with intended emmetropia (ZKB00 group: 20 eyes) were included in this study. Visual acuity at 4 m, 80, and 40 cm; and the types of halos (misty, fine, and rainbow) were analyzed at one and three months after surgery. RESULTS: There were no significant differences in distance visual acuity among the three groups. The mean uncorrected intermediate visual acuity was better in the ZXR00 emmetropia and monovision groups (0.02 logMAR and 0.02 logMAR, respectively) than in the ZKB00 group (0.14 logMAR). The mean uncorrected near visual acuity was worse in the ZXR00 emmetropia group (0.26 logMAR) than in the ZXR00 monovision and ZKB00 groups (0.12 logMAR and 0.10 logMAR, respectively). There was an increased incidence of rainbow halos in the ZKB00 group vs in either ZXR00 group (P=0.033). CONCLUSION: Implantation of the ZXR00 IOL with intended micromonovision provide superior visual acuity than implantation of the ZXR00 IOL with intended emmetropia. The ZXR00 IOLs tend to show a lower incidence of rainbow halos than did the ZKB00 IOL.

Multizonal Design Multifocal Intraocular Lens-Induced Astigmatism According to Orientation.

PURPOSE: To evaluate the differences in intraocular lens (IOL)-induced astigmatism according to differences in orientation of a multizonal multifocal IOL, the Precizon Presbyopic NVA IOL (Ophtec BV). METHODS: The clinical study reviewed 80 eyes from 40 patients with cataracts who underwent Precizon Presbyopic IOL implantation. Residual astigmatism, as measured by autorefraction and manifest refraction, was investigated using vector analysis of eyes implanted with vertical (90 ± 30 degrees) and horizontal (180 ± 30 degrees) orientations of the first near segment of the IOL. In the ray-tracing simulation study, pseudophakic eyes with the Precizon Presbyopic IOL were modeled. The modulation transfer function (MTF) of each case was compared with respect to the amount of corneal astigmatism of the model eyes and the orientation of the first near segment. RESULTS: The mean IOL-induced astigmatism measured by autorefraction was 0.68 ± 0.58 diopters (D) at 1 degree in the vertical orientation of the first near segment (n = 52) and 1.05 ± 0.81 D at 96 degrees in the horizontal orientation (n = 28). However, the mean IOL-induced astigmatism measured by manifest refraction was 0.14 ± 0.44 D at 171 degrees and 0.46 ± 0.40 D at 95 degrees. The MTF analysis showed that the highest MTF values were measured in eyes without corneal astigmatism in both the vertically and horizontally implanted IOLs. CONCLUSIONS: Autorefraction measurement indicates induction of with-the-rule astigmatism by the Precizon Presbyopic IOL when implanted vertically with respect to the first near segment, and against-the-rule astigmatism when implanted horizontally. However, this astigmatism is clinically insignificant according to manifest refraction and ray-tracing simulation. [J Refract Surg. 2020;36(11):740-748.].

Direct measurement of the ciliary sulcus diameter by 35-megahertz ultrasound biomicroscopy.

PURPOSE: To measure the ciliary sulcus diameters in 4 different axes and to determine the correlation with white-to-white distance. DESIGN: Cross-sectional observational study. PARTICIPANTS: Fourteen normal volunteers with no evidence of ocular disease. METHODS: Twenty-eight eyes were scanned using a 35-megahertz (MHz) ultrasound biomicroscopy (UBM) in sequential meridional scan planes at 45 degrees increments. Horizontal white-to-white distance was measured using Orbscan IIz (Bausch & Lomb-Orbtek, Inc., Salt Lake City, UT). MAIN OUTCOME MEASURES: Ciliary sulcus diameter, anterior chamber diameter, white-to-white distance, and coefficient of variation. RESULTS: The coefficient of variation for 35-MHz UBM was 0.90%. The mean diameters+/-standard deviations of ciliary sulci were 11.55+/-0.38 mm at 45 degrees, 11.99+/-0.36 mm at 90 degrees, 11.54+/-0.36 mm at 135 degrees, and 11.32+/-0.40 mm at 180 degrees. In all eyes, vertical diameters were greater than horizontal diameters. The mean difference between vertical and horizontal diameters was 0.67+/-0.26 mm (range, 0.36-1.13 mm), and this was statistically significant (P<0.001). Horizontal sulcus diameters and horizontal white-to-white distances were not correlated (r = 0.006; P = 0.976). CONCLUSIONS: The posterior chamber appears to have a vertically oval shape. The white-to-white technique is inaccurate at predicting the horizontal diameter of the ciliary sulcus. The 35-MHz UBM may provide a good means of measuring the ciliary sulcus diameter for the implantation of a posterior chamber phakic intraocular lens.

Comparison of anterior chamber depth measurement between Orbscan IIz and ultrasound biomicroscopy.

PURPOSE: To compare the measurement of anterior chamber depth exclusive of corneal thickness using Orbscan IIz and ultrasound biomicroscopy (UBM) and evaluate the repeatability of each method. METHODS: Three consecutive measurements of anterior chamber depth were prospectively performed using Orbscan IIz and Paradigm 50-MHz UBM in 40 eyes in 20 individuals. Mean values were compared using the paired t test. For 12 eyes in 6 individuals, anterior chamber depth measurements were performed 5 times to estimate the repeatability of each method by a coefficient of variation. Refractive errors were measured to correlate with anterior chamber depth. RESULTS: The mean anterior chamber depth was 2.82 +/- 0.46 mm with the Orbscan IIz and 2.91 +/- 0.43 mm in UBM. This difference was statistically significant (P < .001), but not clinically meaningful. The coefficient of variation was 1.15% and 1.10% in Orbscan IIz and UBM, respectively. A negative correlation between anterior chamber depth and spherical equivalent refraction was noted within the range of -5.50 to +3.00 diopters. CONCLUSIONS: The mean anterior chamber depth of Orbscan IIz was 0.087 mm less than that of UBM. Both methods were precise. Orbscan IIz seems to be a useful and more convenient method to measure anterior chamber depth for phakic intraocular lens implantation.

Mitomycin-C concentration in cornea and aqueous humor and apoptosis in the stroma after topical mitomycin-C application: effects of mitomycin-C application time and concentration.

PURPOSE: To evaluate the effects of the applied mitomycin-C (MMC) concentration and application time on the aqueous MMC concentration and apoptosis in the corneal stroma. METHODS: New Zealand white rabbits underwent mechanical epithelium debridement of the central 7.5 mm of the cornea. A sponge soaked in MMC solution was placed on the denuded corneal stroma. The effect of the exposure times ranging from 15 to 120 seconds and the different MMC concentrations ranging from 0.005% to 0.04% on the aqueous MMC concentration and the apoptosis in the stromal cells were evaluated. RESULTS: The aqueous concentration of MMC increased linearly with increasing exposure time and MMC concentration. The correlation between the aqueous MMC concentration and the applied concentration (r = 0.809, P < 0.001) was higher than the correlation between the aqueous MMC concentration and the application time (r = 0.693, P < 0.001). Terminal deoxyribonucleotidyltransferase-mediated dUTP-digoxigenin nick end labeling (TUNEL)-positive cells were detected in the superficial stroma of the central denuded cornea. The numbers of TUNEL-positive cells increased linearly with increasing concentrations, and the increase was statistically significant (P = 0.026). However, the numbers of TUNEL-positive cells increased only slightly with an increasing application time, and the increase was not statistically significant (P = 0.928). CONCLUSIONS: Reducing the applied concentration or decreasing the exposure time might be a good modality for reducing the potential MMC toxicity. The applied MMC concentration had greater effects on the aqueous MMC concentration and apoptosis in the stromal cells than the exposure time.

Fabrication of a gold nanoparticles decorated carbon nanotubes based novel modified electrode for the electrochemical detection of glucose.

A modified electrode based on gold nanoparticles decorated multiwall carbon nanotubes (MWNTs), MWNT-Au(nano)-ME is fabricated. MWNTs are functionalized with 4-aminothiophenol and coated over the glassy carbon electrode. Further, Au nanoparticles are deposited into MWNTs coated GC electrode by electrochemical reduction of HAuCl4. Field emission transmission electron microscope (FETEM) image shows the formation of approximately 5 nm sized Au nanoparticles without any agglomeration on the MWNTs surface. Further, the presence of Au nanoparticles is confirmed through X-ray photoelectron spectroscopic (XPS) studies. The electrocatalytic activity of the MWNT-Au(nano)-ME towards the detection of glucose is investigated. MWNT-Au(nano)-ME shows enhanced current response than pristine MWNT-ME over the entire (+0.05 to +0.80 V) potential range. The modified electrode shows linear response to current with the concentration of glucose between 1 and 20 mM. Larger current responses to glucose oxidation are witnessed at +0.60 V than at +0.05 V. However, a large interference signal, reflecting the accelerated oxidation of electroactive interference is observed at +0.60 V. No overlapping signal from the interferents such as ascorbic acid, acetaminophen, and dopamine are observed at the MWNT-Au(nano)-ME at +0.05 V. Further, the MWNT-Au(nano)-ME shows high resistance to the toxictiy of chloride ions.

Ring-shaped dysphotopsia associated with posterior chamber phakic implantable collamer lenses with a central hole.

PURPOSE: To evaluate the incidence of central hole-induced ring-shaped dysphotopsia after posterior chamber phakic implantable collamer lens (ICL) with central hole (hole ICL) implantation and to investigate the causes of central hole-induced dysphotopsia. METHODS: The clinical study enrolled 29 eyes of 15 consecutive myopic patients implanted with hole ICL. The incidence of ring-shaped dysphotopsia after hole ICL implantation was evaluated. In the experimental simulation study, non-sequential ray tracing was used to construct myopic human eye models with hole ICL and ICL without a central hole (conventional ICL). Simulated retinal images measured in log-scale irradiance were compared between the two ICLs for an extended Lambertian light-emitting disc object 20 cm in diameter placed 2 m from the corneal vertex. To investigate the causes of hole-induced dysphotopsia, a series of retinal images were simulated using point sources at infinity with well-defined field angles (0 to -20°) and multiple ICL models. RESULTS: Of 29 eyes, 15 experienced ring-shaped dysphotopsia after hole ICL implantation. The simulation study using an extended Lambertian source showed that hole ICL-evoked ring-shaped dysphotopsia was formed at a retinal field angle of ±40°. Component-level analysis using a well-defined off-axis point source from infinity revealed that ring-shaped dysphotopsia was generated by stray light refraction from the inner wall of the hole and the posterior ICL surface. CONCLUSION: Hole ICL-evoked ring-shaped dysphotopsia was related to light refraction at the central hole structure. Surgeons are advised to explain to patients the possibility of ring-shaped dysphotopsia after hole ICL implantation.

Inadvertent stromal dissection during mechanical separation of the corneal epithelium using an epikeratome.

Epithelial flap complications occurred in 2 patients during epithelial separation using a Centurion SES epikeratome (Norwood Eye Care) in epi-laser in situ keratomileusis (LASIK). The complications consisted of stromal dissection at the margin of the pupil and an epithelial free cap including the superficial stroma. The epithelial flaps were repositioned without laser ablation. Three months postoperatively, the best corrected visual acuity in both patients was 20/20 and neither complained of visual discomfort. Slitlamp biomicroscopic examination showed that both corneas were completely healed with trace opacity, and topographic examinations revealed that irregularities in the stromal cutting sites were decreased. The patients had successful photorefractive keratectomy after complete healing of the dissected stroma. Stromal dissection during mechanical separation of the epithelium with an epikeratome is a potential complication of the epi-LASIK procedure, but proper management can result in good recovery without severe visual impairment.

Infectious keratitis caused by Stenotrophomonas maltophilia and yeast simultaneously.

PURPOSE: To report a case of coinfection of the human cornea by Stenotrophomonas maltophilia and yeast. METHODS: A 59-year-old woman presented with a corneal ulcer. The corneal lesion worsened suddenly after initial improvement with empirical antibiotic treatment. A culture revealed S. maltophilia. The keratitis rapidly progressed despite treatment with sensitivity-proven antibiotic agents. Eventually, the patient underwent therapeutic penetrating keratoplasty. RESULTS: Pathology of the cornea showed yeast forms and pseudohyphae scattered over the cornea. After surgery, the inflammation was controlled without any signs of recurrent infection. CONCLUSION: Coinfection of the cornea by S. maltophilia and yeast may occur in a susceptible cornea and may not be controlled by standard medical treatment.

Concentrations of mitomycin C in rabbit corneal tissue and aqueous humor after topical administration.

PURPOSE: To study the aqueous and corneal pharmacokinetics of mitomycin C (MMC) after single topical administration to the central cornea and to evaluate the effects of different concentrations and different application times on the aqueous concentration of MMC. METHODS: Mechanical epithelium debridement of the central 7.5 mm of the cornea was performed in New Zealand white rabbits, and a sponge soaked in 0.02% MMC solution was placed on the denuded corneal stroma for 2 minutes. Aqueous fluid and central corneal tissues samples were taken at 0.5, 1, 2, and 3 hours thereafter. MMC concentration of the samples was analyzed by high-performance liquid chromatography and evaluated at different exposure times (range: 15-120 seconds) and concentrations of applied MMC (range: 0.005%-0.04%). RESULTS: Peak corneal concentration was 3.728 +/- 2.547 microg/g at 30 minutes after topical administration. Maximum aqueous concentration was 0.380 +/- 0.038 microg/mL at 1 hour after topical application. The aqueous concentration of MMC increased in a dose-dependent manner with increasing exposure time and application concentration. Aqueous MMC concentration increased at a higher rate with change of applied concentration than with exposure time. CONCLUSION: Good penetration of MMC through central bare cornea may be noxious to endothelial cells. Reducing concentration or decreasing exposure time seems a good modality to reduce potential MMC toxicity.

Fabrication and electrocatalysis of self-assembly directed gold nanoparticles anchored carbon nanotubes modified electrode.

A self-assembly directed approach was adopted to modify glassy carbon electrode (GC) with gold nanoparticles incorporation and the electrocatalytic performance of self-assembly modified electrode, GC/SA-Au-ME was critically evaluated for the oxidation of ascorbic acid (AA). The modification involves the dispersion of multi-wall carbon nanotube (MWNT) and an inclusion complex, beta-cyclodextrin-4-aminothiophenol on the surface of GC electrode in the presence of cetyltrimethylammonium bromide (CTAB). Gold nanoparticles were deposited into the self-assembled sites to fabricate the modified electrode, GC/SA-Au-ME. Another electrode (GC-Au-ME) was fabricated under similar conditions in the absence of CTAB. The electrocatalytic activity of the modified electrodes (GC/SA-Au-ME and GC-Au-ME) towards the oxidation of AA was critically compared. Cyclic voltammetry, chronoamperometry, and double potential chronoamperometry were used to evaluate the characteristics of the modified electrodes. The self-assembled electrode (GC/SA-Au-ME) shows excellent electrocatalytic activity over the other electrode, GC-Au-ME. Augmented current response, faster electron transfer kinetics (with a rate constant for electron transfer process as 3.25 x 10(4) cm3 mol(-1) s(-1)), linear range of response for the analyte (1-50 mM with an extended detection limit to 1 microM), better sensitivity, and selectivity were witnessed for the self-assembly directed modified electrode.

Antielevation syndrome after unilateral anteriorization of the inferior oblique muscle.

PURPOSE: To report antielevation syndrome with restriction of elevation on abduction in the operated eye and overaction (OA) of the inferior oblique muscle (IO) of the contralateral eye after unilateral IO anteriorization (AT). METHODS: Medical records were reviewed retrospectively in 8 of 24 patients who underwent unilateral IOAT. Four patients were referred from other hospitals after the same surgery. RESULTS: Four patients had infantile esotropes. The rest showed accommodative esotropia, superior oblique palsy, exotropia, and consecutive exotropia. The mean amount of hyperdeviation was 16.3 PD (10 approximately 30). The mean restriction of elevation on abduction in the operated eye was -1.6 (-1 approximately -4) and IOOA of the contralateral eye was +2.7 (+2 approximately +3). IOAT of nonoperated eyes in 4 patients, IO weakening procedure of anteriorized eyes in 2 patients, and IO myectomy on an eye with IOAT in 1 patient were performed. Ocular motility was improved after surgery in all patients. CONCLUSIONS: Unilateral IOAT may result in antielevation syndrome. Therefore bilateral IOAT is recommended to balance antielevation in both eyes. A meticulous caution is needed when performing unilateral IOAT.

Inadvertent ocular perforation during lid anesthesia for hordeolum removal.

PURPOSE: Ocular perforation during lid anesthesia is rarely reported. We describe here a case of inadvertent corneal perforation and traumatic cataract that occurred during lid anesthesia in a procedure for hordeolum removal. METHODS: A 33-year-old woman presented with a sudden visual loss of her left eye. She had undergone hordeolum removal the day before at a local clinic. On ophthalmologic examination, the cornea was perforated and the lens cortex was extruded into the anterior chamber. After cataract removal and IOL implantation, antibiotics were injected into the vitreous. RESULTS: Her final visual acuity of the left eye was 20/20. Postoperative specular microscopic examination revealed a normal-range endothelial cell count, coefficient of variation, and hexagonality despite the intracameral lidocaine injection. CONCLUSIONS: Anesthetic injection of an infected lid should be done with great caution. Although there are possibilities of corneal endothelial toxicity and endophthalmitis in case of intracameral lidocaine injection through the infected lid, yet proper management may save the patient's vision without complications.

Electrochemical determination of dopamine and ascorbic acid at a novel gold nanoparticles distributed poly(4-aminothiophenol) modified electrode.

A modified electrode is fabricated by embedding gold nanoparticles into a layer of electroactive polymer, poly(4-aminothiophenol) (PAT) on the surface of glassy carbon (GC) electrode. Cyclic voltammetry (CV) is performed to deposit PAT and concomitantly deposit Au nanoparticles. Field emission transmission electron microscopic image of the modified electrode, PAT-Au(nano)-ME, indicates the presence of uniformly distributed Au nanoparticles having the sizes of 8-10nm. Electrochemical behavior of the PAT-Au(nano)-ME towards detection of ascorbic acid (AA) and dopamine (DA) is studied using CV. Electrocatalytic determination of DA in the presence of fixed concentration of AA and vice versa, are studied using differential pulse voltammetry (DPV). PAT-Au(nano)-ME exhibits two well defined anodic peaks at the potential of 75 and 400mV for the oxidation of AA and DA, respectively with a potential difference of 325mV. Further, the simultaneous determination of AA and DA is studied by varying the concentration of AA and DA. PAT-Au(nano)-ME exhibits selectivity and sensitivity for the simultaneous determination of AA and DA without fouling by the oxidation products of AA or DA. PAT and Au nanoparticles provide synergic influence on the accurate electrochemical determination of AA or DA from a mixture having any one of the component (AA or DA) in excess. The practical analytical utilities of the PAT-Au(nano)-ME are demonstrated by the determination of DA and AA in dopamine hydrochloride injection and human blood serum samples.