Pattern visual evoked potentials in the assessment of objective visual acuity in amblyopic children

The aim of this study was to determine the value of pattern visual evoked potentials (PVEP) to five consecutive check size patterns in the assessment of visual acuity (VA) in children. One hundred unilateral amblyopic (study group) and 90 healthy children with best-corrected visual acuity (BCVA) of 1.0 (control group) were planned to be included. PVEP responses to five consecutive check sizes (2°, 1°, 30′, 15′, and 7′) which are assumed to correspond to VAs of 0.1, 0.2, 0.4, 0.7 and 1.0 Snellen lines were recorded in both groups. Eighty-five children in the study group (85.0%) and 74 children in the control group (82.2%) who cooperated well with PVEP testing were included. Normal values for latency, amplitude, and normalized interocular amplitude/latency difference in each check size were defined in the control group. PVEP-estimated VA (PVEP-VA) in the amblyopic eye was defined by the normal PVEP responses to the smallest check size associated with normal interocular difference from the non-amblyopic eye, and was considered predictive if it is within ±1 Snellen line (1 decimal) discrepancy with BCVA in that eye. Mean age was 9.7 ± 1.9 and 9.9 ± 2.2 years in the study and the control groups, respectively. LogMAR (logarithm of minimum angle of resolution) Snellen acuity was well correlated with the logMAR PVEP-VA (r = 0.525, P < 0.001) in the study group. The Snellen line discrepancy between BCVA and PVEP-VA was within ±1 Snellen line in 57.6% of the eyes. PVEP to five consecutive check sizes may predict objective VA in amblyopic children.     

Applications of the isolated-check visual evoked potential in primary open angle glaucoma with or without high myopia

AIM: To determine whether the different diameters of a specific intraocular lens (IOL) have significantly different optimised SRK/T A constants and whether these new A constants can improve refractive outcomes. METHODS: Data were collected prospectively from Jan 2011 - Dec 2012 on all patients undergoing routine cataract surgery at a district general hospital in the UK. Patients were divided into three groups according to the size of the Akreos AO MI60 IOL used. A constant for the SRK/T formula were optimised according to the size of the IOL. These optimised A constants were then used to select future refractive outcomes. RESULTS: Totally 2398 cataract operations were performed during the study period of which 1131 met the inclusion criteria. The three optimised A constants for the different sized IOLs were 118.98, 119.13 119.32. The difference between them was highly significant (P≤0.0001). Two optimised A constants for three sizes of IOL led to an improvement in refractive outcomes (from 93.4% to 94.6% of refractive outcomes within 1.00 D of predicted spherical equivalent). The optimised A constant for the largest IOL was based on a small number of cases and was not used. CONCLUSION: Optimising the A constant for the three distinct sizes of the Bausch & Lomb Akreos MI60 lens lead to three significantly different A constants. In our practice, using two different optimised A constants for three different sized IOLs give the least refractive error, however, using three optimised A constants may give better results with a larger dataset.     

Effect of posterior juxtascleral triamcinolone acetonide on the efficacy and choriocapillaris hypoperfusion of photodynamic therapy

Purpose To evaluate the effect of posterior juxtascleral triamcinolone acetonide (TA) injection combined with photodynamic therapy with verteporfin (PDT) for treating exudative age-related macular degeneration (AMD), the best-corrected visual acuity (BCVA), the retreatment rates and the rate of choroidal hypoperfusion were investigated. Methods A total of 67 eyes with subfoveal choroidal neovascularization (CNV) due to AMD were included. Forty-four eyes underwent PDT alone (PDT-alone group), and 23 eyes underwent PDT with the posterior juxtascleral injection of TA (PDT+TA group). Every 3 months after the PDT, the eyes were evaluated with regard to BCVA and requirement for retreatment by fluorescein angiography (FA) with the aid of optical coherence tomography (OCT). Choroiocapillaris hypoperfusion was assessed by indocyanine green angiography (ICGA) at 3 and 12 months. All patients completed a 1-year follow-up. Results At the baseline, there was no difference in lesion type, size or visual acuity between the two groups. At 1 year, the change in BCVA was −0.0811 logarithm of the minimum angle of resolution (LogMAR) in the PDT-alone group, compared with −0.0432 logMAR in the PDT+TA group. There was no significant difference in the change in BCVA between the two groups (P = 0.6910). The PDT+TA group required a lower mean number of treatments (1.64 compared with 2.34 [P = 0.0223]) and showed a higher rate of choriocapillaris occlusion at 3 months, but no significant difference at 1 year (P = 0.9243) Conclusions Fewer retreatments were required in the TA+PDT group. There was no significant difference in the change in BCVA between the two groups. Adjacent TA may promote short-term choriocapillaris hypoperfusion.     

Comparing isolated-check visual evoked potential,pattern visual evoked potential,and standard automated perimetry in dysthyroid optic neuropathy eyes

ObjectiveTo determine the diagnostic ability of isolated-check visual evoked potential (icVEP), pattern visual evoked potential (pVEP), and standard automated perimetry (SAP) between dysthyroid optic neuropathy (DON) and thyroid-associated ophthalmopathy (TAO) without DON (non-DON).MethodsThis is a case-control study, 49 bilateral patients (26 DON and 23 non-DON) were included. icVEP, pVEP, and SAP were conducted in all the subjects, icVEP parameters compared were signal-to-noise ratios (SNRs) under 8, 16, and 32% depth of modulation (DOM). pVEP parameters compared were amplitude and latency. SAP parameters were mean deviation (MD) and pattern standard deviation (PSD). The area under the receiver operating characteristic (ROC) curve (AUC), net reclassification index (NRI), integrated discrimination index (IDI), and decision curve analysis (DCA) were applied for analysis.ResultsIn icVEP, values of SNR in DON were significantly smaller than non-DON (p < 0.05). In pVEP, P100 latent time in DON was significantly larger than non-DON (p = 0.0026). In SAP, value of PSD in DON was larger than non-DON (p = 0.0006), and value of MD in DON was smaller (p = 0.0007). AUC, NRI, and IDI among the three tests were not significantly different. DCA showed that SNR of icVEP under 8% DOM was the farthest from the two extreme curves.ConclusionsicVEP, pVEP, and SAP have equal diagnostic capabilities to discern between DON and non-DON. In addition, icVEP may represent a significant ancillary diagnostic approach to DON detection, with more clinical benefit.Subject terms: Optic nerve diseases, Autoimmune diseases     

Comparison of contrast sensitivity,depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration

Purpose  To compare the clinical performance of the zero spherical aberration (SA) SofPort LI61AO (AO, Bausch & Lomb) intraocular lens (IOL) to the AcrySof SA60AT (AT, Alcon), which has positive spherical aberration. Methods  Patients underwent uneventful phacoemulsification with implantation of either an aspheric (AO, n = 19) or spherical (AT, n = 20) IOL. Postoperatively, a 5 mm artificial pupil was positioned in trial frames with the cycloplegic refraction during monocular, mesopic contrast sensitivity (CSF) and low-contrast visual acuity (LCVA) testing with glare. Ocular and corneal wavefront error was determined at 5 mm diameters. Results  Mean CSF scores were better at all frequencies tested for the AO than for the AT group, and achieved statistical significance at 1.5 cpd (p = 0.038) and 6 cpd (p = 0.017). With glare, AO eyes read 30.9 ± 5.0 low-contrast letters versus 25.2 ± 6.8 for AT eyes (p = 0.005) (mean ΔLogMAR  =  −0.10), while high-contrast acuity and refraction were similar. Eyes implanted with the SA60AT had 43% greater positive spherical aberration at a 5 mm wavefront diameter, with no significant difference in corneal SA between groups. A through-focus analysis demonstrated a similar depth of field, yet a comparatively higher visual Strehl ratio for the aspheric IOL at emmetropia (p = 0.038). Conclusion  Eyes with the SofPort Advance Optics neutral aberration IOL demonstrated less spherical aberration and better low-contrast acuity compared to eyes with a spherical IOL, without sacrificing tolerance to defocus. The aspheric IOL showed superior optical and clinical performance, which is most likely due to its surface design. Supported in part by research grants from the Midwest Cornea Foundation, St. Louis, MO, USA and Bausch & Lomb, Rochester, NY, USA. Drs. Pepose, Qazi and Sanderson have no financial interest in the products described. Dr. Pepose has received research and travel support from Bausch & Lomb. Dr. Sarver has a financial interest in the VOL-CT Software used in this study. Mr. Edwards is an employee of Bausch & Lomb. Dr. Pepose is a paid consultant for Bausch & Lomb, Rochester, NY, USA     

Assessing the impact of non-dilating the eye on full-field electroretinogram and standard flash response

We investigated the possibility of performing electroretinography (ERG) in non-pharmacologically dilated eyes using brighter flash (time-integrated) luminance. Photopic (N = 26; background 25.5 cd·m⁻², white LED flashes) and scotopic ERG (N = 23, green LED flashes) luminance response functions were obtained simultaneously in a dilated (DE) and non-dilated eye (NDE). In the NDE, photopic V _max b-wave amplitude was reduced by 14% (P < 0.0001), implicit time prolonged (P < 0.0001), and retinal sensitivity (log K) decreased by 0.38 log units (P < 0.0001) with no effect on a-wave. Using a xenon strobe light (N = 6) to increase flash luminance, V _max remained lower by about 12% in the NDE (P = 0.02). V _max with LED and xenon was achieved at 3.9 ± 1.0 cd·s·m⁻² and 3.3 ± 0.81 cd·s·m⁻² in the DE and 10.6 ± 1.2 cd·s·m⁻² and 12.3 ± 1.90 cd·s·m⁻² in the NDE, that is an increase of 0.43 and 0.57 log unit (P < 0.0001), respectively. Increasing background luminance by 0.50 log units (80 cd·m⁻², N = 4) resulted in implicit time normalization but not V _max amplitude. Rod V _max was decreased by 7% in NDE (P < 0.05) and sensitivity reduced by 0.40 log units (P < 0.0001), but our data suggest that the luminance may have not been sufficient to reach V _max in all participants in the NDE and that the sensitivity change may have been due to an inadequate inter-stimulus interval. For the photopic ERG, increasing flash luminance is not sufficient to compensate for the smaller pupil size, whereas for the scotopic ERG, more data are needed to establish proper inter-stimulus interval to perform recordings in a non-pharmacologically dilated.     

The relationship between central corneal thickness and degree of myopia among Saudi adults

Purpose To determine the relationship between central corneal thickness (CCT) and myopia among Saudi adults. Methods In a prospective study, the CCT of 982 myopic eyes and 158 emmetropic eyes as a control group was measured using ultrasound pachymetry at the Eye Consultants Center, Riyadh, Saudi Arabia. Result The mean myopic spherical equivalent (SE) was −3.7 ± 2.12 D, range −0.25 to −15.0 D.The mean CCT of the myopic group was 543.8 ± 35.40 μm, while for the emmetropic group it was 545.7 ± 27.6 μm. The difference in mean CCT between the two groups was statistically insignificant (P = 0.5). There was no correlation between CCT and the degree of myopic spherical equivalent (r = −0.014, P = 0.939). Conclusion This clinical study showed that there was no difference in CCT between emmetropic and myopic eyes. CCT did not correlate with the degree of myopia. It seems that the central cornea is not significantly involved in the process of myopic progression.     

Intravitreal infliximab for refractory pseudophakic cystoid macular edema: results of the Pan-American Collaborative Retina Study Group

Inflammation is the major etiologic factor in the development of pseudophakic cystoid macular edema (CME). Several soluble mediators of inflammation such as tumor necrosis factor alpha (TNF-α) have been implicated in the pathogenesis of ocular inflammation. The purpose of this study is to report the short-term visual and anatomic outcomes following intravitreal injections of infliximab in eyes with refractory CME secondary to cataract surgery. An interventional, retrospective study of 7 eyes with refractory CME that were injected with 1 mg of infliximab. The main outcome measures were best-corrected visual acuity (BCVA) and central macular thickness (CMT) at 6-month follow-up. At the 6 month follow-up, BCVA improved from 1.14 ± 0.59 logMAR at baseline to 0.51 ± 0.35 logMAR (p = 0.0156). CMT also improved from 584 ± 159 μm at baseline to 327 ± 127 μm at 6 months (p = 0.0111). No systemic adverse events were reported in these patients. There was a single episode of uveitis that responded to topical steroids. Inhibition of TNF-α may be beneficial in the treatment of refractory pseudophakic CME.     

The impact of penetrating keratoplasty in patients with keratoconus using the VF-14 questionnaire

To assess the visual function of patients with keratoconus who underwent penetrating keratoplasty with the use of the VF-14 questionnaire. Fourteen patients (9 male and 5 female) with a mean age of 38 years (SD 13.59) participated in the study. All patients had keratoconus, confirmed by corneal topography, and all had previously undergone penetrating keratoplasty in one eye. Their mean best-corrected visual acuity (BCVA) binocularly was 0.185 (SD 0.077) LogMAR. None of the grafted eyes had a BCVA <0.300 LogMAR. Fourteen healthy volunteers, age- and sex-matched, also participated in the study as control subjects. The VF-14 questionnaire was used to evaluate the effect of the ocular status in the daily life activities of the patients. The mean VF-14 result for the grafted patients with keratoconus was 62.37% (SD 22.60) and for the control group it was 100% (P < 0.001). There was only a weak correlation between the VF-14 score and the binocular BCVA (r = −0.394, P = 0.163). The mean VF-14 result in grafted patients with keratoconus is indicative of low functional ability despite the satisfactory postoperative BCVA. The absence of a significant correlation between the VF-14 score and the mean BCVA indicates that the low functional visual ability in these patients is probably associated more with the ‘perceived by themselves’ difficulty due to their ophthalmological condition.     

Effect of different stimulus configurations on the visual evoked potential (VEP)

The purpose of this study was to assess changes in the response profile of the pattern visual evoked potential (VEP) using three stimulus configurations simulating visual-field scotomas: central circular and central blank fields increasing incrementally in diameter from 1° to 15°, hemi-field, and quadrant patterns. Five visually normal adult subjects (ages 22–68 years) were tested binocularly at 1 m for each stimulus configuration on 5 separate days. A checkerboard test pattern (64 × 64 black-and-white checks, 85 % contrast, 64 cd/m² luminance, 20 s of stimulus duration, 2-Hz temporal frequency) was used. The group mean VEP amplitude increased in a linear manner with increase in the central circular diameter (y = 0.805x + 2.00; r = 0.986) and decrease in central blank field diameter (y = −0.769x + 16.22; r = 0.987). There was no significant change in latency in nearly all cases. The group mean coefficient of variability results indicated that the VEP amplitude was repeatable for the different stimulus configurations. The finding of VEP response linearity for the circular stimulus fields, and repeatability for all stimulus configurations, suggests that the clinician may be able to use the VEP technique with the suggested test patterns as a rapid and simple tool for objective assessment for several types of visual-field defects for a range of abnormal visual conditions and special populations.     

Trabeculectomy for advanced glaucoma

The objective of this study is to evaluate the visual prognosis and postoperative course in advanced glaucoma patients who underwent trabeculectomy. The records of 30 patients with advanced visual field (VF) defects undergoing trabeculectomy were retrospectively reviewed. Severe VF defects were defined as those with a sensitivity of ≤5 dB either in more than 85% of test points, excluding the central four points, or in >75% of test points, including three of the central four points with threshold automated perimetry. Main outcome measures were intraocular pressure (IOP), corrected visual acuity (VA) and mean deviation (MD) of VF tests. Mean preoperative IOP, VA and MD values were compared with their respective postoperative values. The latest examination of each patient was used to determine postoperative outcome measures. In addition, any complications encountered were recorded. A total of 34 trabeculectomies were performed. The mean age was 59.3 years (13–80 years). The mean follow-up time was 41.1 months (3–120 months). Preoperatively the mean IOP was 28.4 ± 13.1 mmHg, and the mean postoperative IOP was 14.8 ± 5.0 mmHg (P = 0.001). Preoperatively the mean VA was 0.87 ± 80, and the mean value of the MD was −24.5 ± 6.7 dB. At the latest follow-up there was no significant difference in VA (0.89 ± 79, P = 0.699) and MD (−23.9 ± 6.7, P = 0.244) values. Transient hypotony occured in five eyes while one eye with mitomycin C trabeculectomy experienced extended hypotony. Ten eyes showed reduction of VA between 1 and 5 lines due to cataracts and five eyes had late bleb failure with uncontrolled IOP. One patient had late endophthalmitis and one patient presented with blebitis, both of which were successfully treated. No patients experienced wipe-out phenomenon. In conclusion, our study of advanced glaucoma patients undergoing trabeculectomy, vision was preserved with no cases of unexplained loss of central vision. IOP was largely controllable, with cataract being the leading factor decreasing VA at late term.     

Uncorrected visual acuity in the immediate postoperative period following uncomplicated cataract surgery: bimanual microincision cataract surgery versus standard coaxial phacoemulsification

Aim We compared bimanual microincision cataract surgery (MICS) and standard coaxial phacoemulsification (CAP) in terms of uncorrected visual acuity (UCVA) recorded 1 h and 2 weeks postoperatively. Methods This was a prospective, nonrandomised comparative study. All MICS procedures were performed by one surgeon (MGM), and all CAP procedures were performed by another surgeon (SB). Eyes with visually consequential ocular morbidity were excluded. The primary outcome measure was UCVA recorded 1 h postoperatively. Results One hundred eyes underwent MICS and CAP (50 eyes in each group). The treatment groups did not differ significantly in terms of preoperative mean best corrected visual acuity (6/24 ± 4.3 lines and 6/20 ± 4.4 lines in the MICS and the CAP groups, respectively; P = 0.65). Also, there was no significant difference in terms of postoperative UCVA at 1 h or at 2 weeks (mean ± standard deviation UCVA 1 h postoperatively: MICS: 6/36 ± 5.7 lines; CAP: 6/30 ± 4.7 lines; P = 0.80; UCVA 2 weeks postoperatively: MICS: 6/10 ± 1.9 lines; CAP: 6/10 ± 2.2 lines; P = 0.90). However, nine eyes (18%) and one eye (2%) achieved a UCVA of ≥6/12 at 1 h following MICS and CAP, respectively, and this difference was statistically significant (P = 0.02). Conclusion Mean UCVA at 1 h and at 2 weeks following cataract surgery was not significantly different between eyes undergoing MICS and CAP. However, a greater proportion of patients achieved a UCVA of ≥6/12 following MICS when compared with CAP.     

Assessment of patients with suspected non-organic visual loss using pattern appearance visual evoked potentials

Background The aim of the study was to validate the use of the short duration pattern onset visual evoked potential (PappVEP) in the objective assessment of visual acuity (VA) in patients referred with presumed non-organic visual loss. Methods The combination of minimum check size and minimum contrast required to elicit a consistently discernible PappVEP (amplitude ≥5 μV) were measured in ten normal subjects under conditions of induced optical blur (0 to +3 dioptres) and the relationship to Snellen VA established. The data from 100 consecutive patients (167 eyes) referred for possible non-organic visual loss (NOVL) and 20 patients with confirmed visual pathway dysfunction were reviewed in relation to the results in normal subjects. Results Snellen VA, under conditions of blur, could be predicted in normal subjects from the check size and contrast required to elicit a criterion PappVEP. These data were tabulated and a quantitative guideline established for the estimation of VA in the patients referred with suspected NOVL. Most (88%) patients referred with suspected NOVL had normal electrophysiology and PappVEPs consistent with normal Snellen VA. In others, they suggested a degree of non-organic overlay. In 20 cases of organic visual loss, PappVEPs were in close agreement with subjective VA. Conclusions The short duration pattern onset visual-evoked potential is confirmed as a clinically useful tool in the objective assessment of patients with suspected non-organic visual loss.     

Receiver-operating characteristic analysis of multifocal VEPs to diagnose and quantify glaucomatous functional damage

To test whether multifocal visual evoked potential (mfVEP) recording using two perpendicularly placed channels, as previously reported, to measure the degree of signal-to-noise ratio (SNR) distribution overlap between a signal window and a noise window would efficiently detect and quantify glaucomatous damage. Humphrey visual field (HVF) and mfVEP were recorded from 56 patients with primary open-angle glaucoma and mean deviation less than −15 dB and 62 age-matched ophthalmologically normal individuals. Areas under the receiver-operating characteristic curve (SNR-AUC) were calculated based on the proportion of mfVEP responses that exceeded a specific SNR criterion for both windows. Abnormal sectors with an SNR deviated from the previously established norm with P < 5% and 1% were counted. Diagnostic accuracy of the SNR-AUC was similar to that of the average total deviation (TD) of the HVF. The hemifield agreement to detect a defect in mfVEP and HVF was 77.1–87.3%, which was similar to previous reports using multiple channels. Correlation coefficients between SNR-AUC and average TD (0.74 in the upper hemifield and 0.65 in the lower) were significantly higher than those between the sums of abnormal locations on the mfVEP and HVF probability plots (0.27 and 0.33, respectively). Two perpendicular channels can detect and quantify functional damage due to glaucoma. The SNR-AUC may be used as a global index to quantify diffuse glaucomatous functional loss.     

Accuracy of isolated-check visual evoked potential technique for diagnosing primary open-angle glaucoma

Purpose

The aim of this study was to determine the diagnostic accuracy, sensitivity and specificity of isolated-check visual evoked potentials (icVEP) in primary open-angle glaucoma (POAG).

Methods

Ninety POAG patients and sixty-six healthy controls were recruited consecutively. All subjects underwent icVEP and visual field testing. Swept icVEP response functions were obtained by increasing contrast in six stimulus steps, recording the electroencephalogram synchronized to the stimulus display’s frame rate and calculating the corresponding signal-to-noise ratio (SNR) of the response at the fundamental frequency to evaluate visual function. Depth of modulation of the check luminance was increased as follows: 2, 4, 8, 14, 22 and 32%, about an equal level of standing contrast, so that the pattern appeared and disappeared at a frequency of 10.0 Hz. SNR above 0.85 was deemed to be significant at the 0.1 level and SNR above 1 significant at the 0.05 level.

Results

The results show that SNR is contrast dependent. It significantly rose as contrast increased. The areas under receiver-operating-characteristic curves (AUCs) indicating classification accuracy for all POAG cases in comparison with normal subjects were 0.790 (sensitivity 91.1%, specificity 69.7%) with the cutoff SNR of 0.85, and 0.706 (sensitivity 95.6%, specificity 51.5%) with the cutoff SNR of 1. The AUC of early glaucoma cases (EG) in comparison with normal subjects was 0.801 (sensitivity 93.3%, specificity 69.7%) with the cutoff SNR of 0.85, and 0.717 (sensitivity 97.8%, specificity 51.5%) with the cutoff SNR of 1.

Conclusion

icVEP has good diagnostic accuracy (high sensitivity and moderate specificity) in distinguishing early POAG patients from healthy subjects. It might be a promising device to use in conjunction with complementary functional and structural measures for early POAG detection.

     

飞秒微透镜边缘阶梯对视觉质量的影响

目的探讨全飞秒微透镜切除术后,光学切削过渡区的“无修边”设计是否影响患者术后视觉质量,特别是瞳孔散大超过光学切削区时。方法前瞻性队列研究。纳入患者共104例（208眼）,其中薄瓣LASIK组38例（76眼）、飞秒LASIK组28例（56眼）、飞秒激光微小切口透镜切除术（SMILE）组 38例（76眼）。薄瓣LASIK组应用准分子激光切削,光学切削区直径6.0 mm,过渡区宽度1.25 mm,总直径8.5 mm;飞秒LASIK组应用飞秒激光制瓣,准分子激光切削,光学切削区直径6.0 mm,过渡区宽度1.25 mm,总直径8.5 mm;SMILE组应用飞秒激光完成微透镜切除,透镜直径设定6.0 mm。术后检查裸眼视力、小瞳（≤5 mm）及大瞳（≥7 mm）的对比敏感度（CS）与眩光敏感度（GS）、波前像差。采用单因素方差分析对数据进行比较。结果术中及术后均无严重并发症发生,术眼裸眼视力3组均达到或超过术前最佳矫正视力。在小瞳（≤5 mm）下,3组患者在各空间频率,无眩光刺激和有眩光刺激下的视觉对比敏感度差异均无统计学意义。在大瞳（≥7 mm）下,3组患者在各空间频率,无眩光刺激和有眩光刺激的视觉对比敏感度差异均无统计学意义。小瞳（≤5 mm）时3组C12比较差异无统计学意义,而大瞳（≥7 mm）时薄瓣LASIK组与飞秒LASIK组比较差异无统计学意义,SMILE组与薄瓣LASIK组、飞秒LASIK组分别比较,差异具有统计学意义（t=2.942,P<0.01;t=3.264,P<0.01）。SMILE组C12值（0.422±0.123）均小于薄瓣LASIK（0.577±0.147）与飞秒LASIK组（0.606±0.158）。结论与设定了过渡区“修边”的薄瓣LASIK组、飞秒LASIK组相比,SMILE组手术的无光学过渡区修边设计对患者术后视觉质量无明显影响。     

Macular thickness after uneventful cataract surgery determined by optical coherence tomography

Background Using standardized macular optical coherence tomography (OCT) in the postoperative period, subclinical changes in macular thickness can be detected. With this method, postoperative development of macular thickness in healthy eyes is evaluated. The repeatability of the method and the influence of selected surgical (phaco time and phaco energy) and biometric parameters (axial length and anterior chamber depth) on the results were assessed. Methods In a prospective study, 33 patients without macular pathology in both eyes were examined. Phacoemulsification and intraocular lens (IOL) implantation was performed in one eye, and the contralateral eye served as control. OCT (StratusOCT; Zeiss, Dublin, CA, USA), mean minimal foveal thickness (MMFT) and mean foveal thickness (MFT) were measured preoperatively, at 1 day, 1 week and 6 weeks postoperatively. At these visits, the best-corrected visual acuity (BCVA) tests and slit-lamp examination were performed. To assess the influence on foveal thickness ocular axial length, anterior chamber depth, phacotime and energy were documented. Statistical analysis using parametric tests was carried out with standard statistical software (SPSS11, BIAS). Results MMFT of the operated eyes and the intraindividual difference of MMFT increased significantly at one day (+12.31 ± 24.2 μm, P < 0.001) and 6 weeks (+6.76 ± 22.6 μm, P = 0.009). MFT in the operated eyes and intraindividual difference of MFT rose significantly at 1 day, 1 week and 6 weeks (1 day: +10.66 ± 20.8 μm, P = 0,026; 1 week: +15.23 ± 19.7 μm; 6 weeks: +17.33 ± 14.81 μm, P < 0.001). Repeatability was better for MFT in controls (ICR = 0.92) than for MMFT in controls (ICR = 0.77). No clinical cystoid macular edema was diagnosed in this study. No correlation between macular thickening and visual acuity and selected surgical and biometrical parameters could be found. Conclusions After cataract surgery, a mild increase of foveal thickness without impact on visual acuity could be observed. This increase may be due to both subclinical changes and to influence of changes in media opacity on the measurement technique. Surgical and biometric parameters such as phacotime and energy and axial length did not correlate to the degree of macular thickening. Presented in part at the meeting of the European Society of Cataract and Refractive Surgeons (ESCRS), London, United Kingdom, September 2006 and at the meeting of the German Ophthalmological Society (DOG), Berlin, Germany, September 2006. The authors have no financial or proprietary interest in any material or method mentioned.     

非球面人工晶状体植入术后偏心和倾斜与视觉质量的相关性研究

目的：探讨新型眼前节扫频光相干断层扫描仪CASIA2测量年龄相关性白内障患者植入非球面人工晶状体(IOL)术后的偏心和倾斜与视觉质量的关系。

方法：观察性研究。纳入年龄相关性白内障术后1mo随访的患者62例90眼。应用CASIA2于散瞳后测量IOL偏心和倾斜的大小和方向,进行3次测量,取其矢量平均值。再使用KR-1W波前像差仪和双通道视觉质量分析系统(OQAS)进行测量,获取4、6mm瞳孔直径下全眼总高阶像差(tHOA)、球面像差(SA)、彗差(Coma)、客观散射指数(OSI)、调制传递函数截止频率(MTF cut off)和斯特列尔比(SR)等参数。

结果：IOL偏心与4mm瞳孔直径下SA(r=0.347,P=0.001)和OSI(r=0.343,P=0.002)成正相关,与MTF cut off(r=-0.244,P=0.032)呈负相关,与tHOA、Coma和SR无相关。IOL倾斜与4mm瞳孔直径下MTF cut off(r=-0.345,P=0.002)和SR(r=-0.256,P=0.023)呈负相关,与tHOA、SA、Coma、OSI均无相关性。IOL的偏心和倾斜与6mm瞳孔直径下的tHOA、SA、Coma、MTF cut off、SR均无相关性。

结论：年龄相关性白内障患者植入非球面IOL后,除IOL偏心与4mm瞳孔直径下SA呈弱相关性,偏心和倾斜与其余各项高阶像差均无明显相关性,与视觉质量参数OSI值及MTF cut off值弱相关,提示临床医生在精准白内障手术中关注高阶像差及视觉质量。     

The effect of mitomycin C trabeculectomy on the progression of visual field defect in normal-tension glaucoma

Background: We investigated in a prospective fashion the visual prognosis and complications in normal-tension glaucoma following unilateral trabeculectomy with adjunctive mitomycin C. Methods: Trabeculectomy with adjunctive mitomycin C was carried out unilaterally in 21 cases of normal-tension glaucoma. Intraocular pressure (IOP), visual prognosis, and complications were compared between the operated eyes and the non-operated fellow eyes. The follow-up period ranged from 2 to 7 years. Results: The IOP dropped significantly from 14.8±1.8 mmHg (mean ± SD) to 9.6±3.9 mmHg in the operated eyes (P=0.0002, Wilcoxon signed-rank test ), but did not drop in the non-operated eyes. The mean deviation (MD) was –12.69±6.41 dB preoperatively and –14.70±5.49 dB at the last clinic visit in the operated eyes, whereas in non-operated eyes it was –7.85±5.65 dB and –11.15± 5.62 dB, respectively. The MD deteriorated significantly in both operated and non-operated eyes (operated eyes P=0.0239, non-operated eyes: P=0.0002; Wilcoxon signed- rank test). The MD slope was –0.37±0.60 dB/year and –0.71± 0.89 dB/year for the operated and non-operated eyes, respectively (P=0.5243, Mann-Whitney U-test). Visual field deterioration was more frequently observed in the non- operated eyes by a pointwise definition of the progression (P<0.05, McNemar test). Visual acuity deteriorated in 6 of the operated eyes and in 5 of the non-operated eyes. Cataract developed in 6 (29%) of the 21 operated eyes, while among the non-operated eyes 4 (19%) developed cataract. Conclusion: Mitomycin C trabeculectomy is effective in delaying progression of visual field defect in normal-tension glaucoma, but complications may arise and cause some visual disturbance. Received: 4 May 1999 Revised version received: 4 August 1999 Accepted: 16 August 1999     

An objective technique to measure the depth-of-focus in free space

Background Determining the depth-of-focus (DOF) objectively in free space is important, as this provides information regarding the range of clear vision under more natural viewing conditions in which target blur, size, and proximal information, as well as other monocular depth cues, are present.Methods The DOF was assessed objectively in free space in young adults [n=20, ages 24.9±3.1years: myopes (n=14), emmetropes (n=5), hyperope (n=1)] by monitoring accommodation continuously using the commercially available Power Refractor II (PR II) under monocular viewing conditions. A high-contrast target (∼83%) subtending a mean visual angle of 2.3 deg was placed on an optical bench at 25 cm (4 D) along the line-of-sight of the viewing right eye and was displaced slowly (∼0.1–0.15 D/s) proximally and distally. This target provided blur, size, and proximal information, and other depth cues, as normally found in free space. The first consistent change in steady-state accommodative baseline level reflected one edge of the DOF. The mean dioptric difference between these distal and proximal endpoints was averaged, and this represented the total objective DOF.Results The group mean total objective DOF (n=20) was ±0.61±0.09 D, with a range from ±0.46 D to ±0.81 D. Repeatability was excellent.Conclusion A technique was developed and tested to measure the DOF in free space objectively. Further development of this technique will allow the assessment of blur perception under more complex natural viewing conditions simulating the everyday environment.