Corneal white-to-white distance and mesopic pupil diameter

·AIM:To study the relationship between corneal white-to- white (WTW) distance and mesopic pupil diameter. ·METHODS:This study is composed of 30 cases that underwent photorefractive keratotomy (PRK). Pupil size measurements were performed with Schwind ORK wavefront analyzer in mesopic conditions. WTW distance was measured with a measuring caliper. Also, A-scan ultrasound examination was performed in all patients. The relationship among the mesopic pupil diameter and age, sex, axial length, lens thickness, anterior chamber depth(ACD), horizontal WTW distance, vertical WTW distance, spherical equivalent, and average keratometry were analyzed with univariate and multivariate regression analysis. ·RESULTS:Mean pupil diameter was (6.39±0.80)mm (range:3.70mm to 7.73mm. Horizontal WTW distance measurements were between 11.00mm and 12.50mm and mean horizontal WTW distance was (11.79±0.43)mm. On the other hand, vertical WTW distances ranged between 10.00mm and 13.00mm, and their mean was(11.42±0.72)mm. Bivariate correlation between pupil diameter and other variables showed that the axial length, ACD, spherical equivalent, and horizontal WTW distance had a moderate correlation with mesopic pupil diameter. Multiple regression analysis revealed that spherical equivalent and horizontal WTW distances were significantly associated with mesopic pupil diameter (R =0.598, R 2=0.358 P =0.02). ·CONCLUSION:This study shows that mesopic pupil diameter is closely related to horizontal WTW distance. These two factors must be taken in consideration together in preoperative ablation zone planning.

Photopic pupil size change in myopic orthokeratology and its influence on axial length elongation

AIM:To explore the photopic pupil size behavior in myopic children undergoing overnight orthokeratology(ortho-k)over 1-year period and its effects on the axial elongation.METHODS:A total of 202 Chinese myopic children were enrolled in this prospective clinical trial.Ninetyfive subjects in ortho-k group and eighty-eight subjects in spectacle group completed the 1-year study.Axial length(AL)was measured before enrollment and every 6mo after the start of ortho-k.The photopic pupil diameter(PPD)was determined using the Pentacam AXL and measured in an examination room with lighting of 300-310 Lx.Stepwise multiple linear regression analysis was used to identify variables contribution to axial elongation.RESULTS:Compared with spectacle group,the average 1-year axial elongation was significantly slower in the ortho-k group(0.25±0.27 vs 0.44±0.23 mm,P<0.0001).In ortho-k group,PPDs significantly decreased from 4.21±0.62 mm to 3.94±0.53 mm after 1mo of lens wear(P=0.001,Bonferroni correction)and the change lasts for 3-month visit.No significantly change during the other follow-up visits was found(P>0.05,Bonferroni correction).The 4.81 mm PPD may be a possible cutoff point in the ortho-k group.Subjects with PPD below or equal to 4.81 mm tended to have smaller axial elongation compared to subjects with PPD above 4.81 mm after 1-year period(t=-3.09,P=0.003).In ortho-k group,univariate analyses indicated that those with older age,greater degree of myopia,longer AL,smaller baseline PPD(PPDbaseline)experienced a smaller change in AL.In multivariate analyses,older age,greater AL and smaller PPDbaseline were associated with smaller increases in AL.In spectacle group,PPD tended to be stable(P>0.05,Bonferroni correction)and did not affect axial growth.CONCLUSION:PPDs experience significantly decreases at 1-month and 3-month ortho-k treatment.Children with smaller PPD tend to experience slower axial elongation and may benefit more from ortho-k.

Detection and Recuperation of Mental Fatigue

Mental fatigue is a complex state that results from prolonged cognitive activity. Symptoms of mental fatigue can include change in mood, motivation, and temporary deterioration of various cognitive functions involved in goal-directed behavior. Extensive research has been done to develop methods for recognizing physiological and psychophysiological signs of mental fatigue. This has allowed the development of many AI-based models to classify different levels of fatigue, using data extracted from eye-tracking device, EEG, or ECG. In this paper, we present an experimental protocol which aims to both generate/measure mental fatigue and provide effective strategies for recuperation via VR sessions paired with EEG and eye tracking devices. This paper first provides a comprehensive state-of-the-art of mental fatigue predictive factors, measurement methods, and recuperation strategies. Then the paper presents an experimental protocol resulting from the state-of-the-art to 1) generate and measure mental fatigue and 2) evaluate the effectiveness of virtual therapy for fatigue recuperation, using a virtual reality (VR) simulated environment. In our work, we successfully generated mental fatigue through completion of cognitive tasks in a virtual simulated environment. Participants showed significant decline in pupil diameter and theta/alpha score during the various cognitive tasks. We trained an RBF SVM classifier from Electroencephalogram (EEG) data classifying mental fatigue with 95% accuracy on the test set. Finally, our results show that the time allocated for virtual therapy did not improve pupil diameter in post-relaxation period. Further research on the impact of relaxation therapy on relaxation therapy should allocate time closer to the standard recovery time of 60 min.

Comparison of corneal measurements in keratoconic eyes using rotating Scheimpflug camera and scanning-slit topography

AIM: To compare the anterior segment measurements obtained by rotating Scheimpflug camera(Pentacam) and Scanning-slit topography(Orbscan IIz) in keratoconic eyes.METHODS: A total of 121 patients, 71 males(58.7%)and 50 females(41.3%)(214 eyes) with the diagnosis of keratoconus(KC) were enrolled in this study. Following diagnosis of KC by slit-lamp biomicroscopic examination, central corneal thickness(CCT), thinnest corneal thickness(TCT), anterior chamber depth(ACD),and pupil diameter(PD) were measured by a single examiner using successive instrumentation by Pentacam and Orbscan.RESULTS: There was no significant difference between the two instruments for the measurement of CCT and TCT. In contrast, scanning-slit topography measured ACD(3.46±0.40 mm vs 3.38±0.33 mm, P =0.019) and PD(4.97 ±1.26 mm vs 4.08 ±1.19 mm, P 【0.001) significantly larger than rotating Scheimpflug camera.The two devices made similar measurements for CCT(95% CI:-2.94 to5.06, P =0.602). However, the mean difference for TCT was-6.28(95% CI:-10.51 to-2.06, P =0.004) showing a thinner measurement by Orbscan than by Pentacam. In terms of the ACD, the mean difference was 0.08 mm(95%CI: 0.04 to 0.12, P 【0.001) with Orbscan giving a slightly larger value than Pentacam. Similarly, Orbscan measurement for PD was longer than Pentacam(95% CI:0.68 to 1.08, P 【0.001).CONCLUSION: A good agreement was found between Pentacam and Orbscan concerning CCT measurement while comparing scanning-slit topography and rotatingScheimpflug camera there was an underestimation for TCT and overestimation for ACD and PD.

Measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients

AIM:To evaluate the measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients.·METHODS:A hundred and one eyes of 55 keratoconus patients were enrolled in this study.The mean age was26.2 ±8.9 years.The inclusion criteria were keratoconus stage I to III according to the Amsler-Krumeich keratoconus classification.All the measurements were done by the same operator,under the mesopic light condition and repeated with three different optical methods;Visante,Orbscan and Pentacam.The evaluated anterior segment parameters were anterior chamber depth(ACD),central and thinnest corneal thickness(CCT and TCT) and pupil diameter(PD).·RESULTS:The mean CCT measured by Visante,Orbscan and Pentacam were as follows:462.0 ±48.1μm,463.9±60.9μm,476.5±45.3μm,respectively(P =0.873).The mean ACD values were 3.34±0.33mm,3.26±0.33mm,3.49±0.40mm,respectively(P=0.118).The mean PD measurements were 5.11 ±1.14mm,4.80 ±0.85mm,3.80 ±1.38mm,respectively(P 【0.001).The mean TCT measurements of Visante,Orbscan and Pentacam were 437.9 ±48.2μm,447.6±60.6μm and 459.9±44.0μm,respectively(P =0.214).The Visante and Orbscan measured CCT similarly,while Pentacam measured CCT thicker than the other two.The Visante measured TCT thinner than the other two devices.In ACD measurements,Orbscan was the one giving the lowest values.PD was measured differently by the devices.·CONCLUSION:Although TCT,CCT and ACD measurements acquired by Visante,Orbscan and Pentacam in keratoconus patients are similar,PDmeasurements show large differences among the devices.

The necessity of pretreatment with 0.1%pranoprofen for femtosecond-assisted cataract surgery:A single-center,randomized controlled trial

Purpose:To explore the effect of the variation of pupil diameter(PD)and intraocular pressure(IOP)induced by femtosecond laser treatment on the subsequent phacoemulsfication and intraocular lens implantation.And whether the application of 0.1%pranoprofen could significantly reduce the miosis and increased IOP caused by femtosecond laser treatment in femtosecond laser-assisted cataract surgery(FLACS).Methods:In this study,patients were pretreated with(trial group)or without(control group)topical 0.1%pranoprofen.The PD and IOP were measured at different time points within 30 min after the completion of the femtosecond laser treatment.Results:The comparisons of the two groups showed the PD of patients pretreated with 0.1%pranoprofen was significantly larger than that of the control only at 15 min after FLACS(P=0.046),and there was no significant difference in IOP at any time point(P>0.05).Neither the ratio of significant miosis(PD≤5 mm)nor intraocular hypertension(IOP≥30 mmHg)was significantly different between the control group(1.72%,6.67%)and the trial group(1%,4.17%)(P>0.05).Conclusions:The PD and IOP of patients undergoing FLACS showed fluctuations within a small range.The rates of significant miosis and intraocular hypertension are very low,it is safe for surgeons to complete the follow-up procedures within 30 min after femtosecond laser treatment.Pretreatment with 0.1%pranoprofen exerted a slight,albeit significant prophylactic effect preventing pupil miosis.However,it provided only a limited benefit in patients undergoing FLACS without other complications.