Effect of pupil dilation on biometric iris recognition systems for personal authentication

Purpose: To study the effect of pupil dilation on a biometric iris recognition (BIR) system for personal authentication and identification. Methods: A prospective, non?randomized, single?center cohort study was conducted on patients who reported for a routine eye check?up from November 2017 to November 2019 (2 years). An iris scanning device “IRITECH?MK2120U” was used to initially enroll the undilated eyes. Baseline scans were taken after matching with the enrolled database. All eyes were topically dilated and matched again with the enrolled database. The Hamming distance (a measure of disagreement between two iris codes) and recognition status were recorded from the device output, and eyes were evaluated by slit?lamp ophthalmoscopy with special emphasis on pupil shape, size, and texture. Results: All 321 enrolled eyes matched after topical dilation. The pupil size had a significant effect on Hamming distance with a P value <0.05. There were no false matches. A correct recognition rate of 100% was obtained after dilation. No loss of iris texture or pupil shape was observed after dilation. Conclusion: A BIR system is a reliable method for identification and personal authentication after pupil dilation. Topically dilated pupils are not a cause for non?recognition of iris scans.

Do static and dynamic pupillary parameters differ according to childhood, adulthood, and old age? A quantitative study in healthy volunteers

Purpose: We aimed to evaluate the normative pupillometry values and mean pupil dilatation speed in healthy individuals in different age groups in our study. Methods: The study group included 180 eyes of 90 healthy volunteers in different age groups. Group 1 consisted of 30 participants between the ages of 6 and 18, group 2 consisted of 30 participants aged 19–40, and group 3 consisted of 30 participants aged 41–75. Scotopic, mesopic, photopic, and dynamic measurements were taken with automatic pupillometry of Sirius Topographer (CSO, Firenze, Italy). The mean pupil dilation speed at the 18th second was calculated according to dynamic measurements. Results: Group 1 had a significantly larger pupil diameter than groups 2 and 3 in all static and dynamic parameters, and the mean pupil dilation speed was the highest among the groups (P < 0.001 for all static and dynamic parameters). In addition, group 2 had a significantly larger pupil diameter than group 3 (P < 0.001 for all static and dynamic parameters) and the mean pupil dilation speed was faster than group 3 (P = 0.027). Conclusion: We have presented the static and dynamic parameters and the mean speed of pupil dilatation at the 18th second with automatic pupillometry in healthy individuals in childhood, adulthood, and old age. More studies with higher participants and younger age children are needed.

Effect of pupil dilation on ocular biometry measurement and IOL power calculation in cataract patients with high myopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the effect of pupil dilation on ocular biometry and IOL power in cataract patients with high myopia, and the difference between cataract patients with high myopia and cataract patients with normal axial length(AL).<p>METHODS:Measurements of AL, corneal curvature(K including K1 and K2), anterior chamber depth(ACD)were performed using IOLmaster in 22 cataract patients with high myopia(34 eyes)(group A)and 23 cataract patients with normal AL(39 eyes)(group B)before and after pupil dilation. SRK-T and Haigis were used to caculate pre- and post-cycloplegic IOL power.<p>RESULTS:ACD after dilation(3.84±0.58mm)significantly increased comparing with ACD before dilation(3.61±0.35mm)in group A(<i>P</i><0.01). ACD after dilation(3.30±0.70mm)also significantly increased comparing with ACD before dilation(3.13±0.63mm)in group B(<i>P</i><0.01). But the difference of pre- and post-cycloplegic ACD between the two groups was not statistically significant(<i>P</i>>0.05). Pre- and post-cycloplegic AL and K(including K1 and K2)were not significantly different in two groups(<i>P</i>>0.05). The differences between pre- and post-cycloplegic IOL power were not statistically significant using the SRK-T and Haigis formula(<i>P</i>>0.05), but the IOL power changed by over 1D after pupil dilation using the SRK-T and Haigis formula respectively in 15% and 27% of eyes in group A,in 3% and 5% in group B.<p>CONCLUSION:ACD increases after pupil dilation in cataract patients with high myopia, which is not different from cataract patients with normal AL. Pupil dilation does not affect AL, K and the IOL power(using SRK-T and Haigis)in cataract patients with high myopia. But the IOL power may change greater than in cataract patients with normal AL, so we suggest IOL power should be measured and calculated without mydriasis.

Intraoperative Floppy Iris Syndrome in patients on alpha 1 blocker tamsulosin: incidence and predictability

Background: Intraoperative Floppy Iris Syndrome (IFIS) was first described by Chang and Campbell in year 2005 in male patients undergoing phacoemulsification surgery who were on Tamsulosin, an alpha 1 blocker drug for their urinary symptoms for enlarged prostate. This condition was characterized by excessive floppiness of iris, prolapse of iris tissue through phaco and sideport incisions and progressive intraoperative miosis, resulting in increased surgical time and various major surgical complications compromising visual outcome.Methods: This study of 78 patients was undertaken to know the incidence and severity of IFIS as well as to predict its occurrence by observing maximum pupil dilation achieved preoperatively.Results: It was observed that majority of patients on tamsulosin dilated poorly and severe IFIS occurred in those with pupil dilation of 5 mm or less after putting mydriatic eye drops preoperatively.Conclusions: It was concluded that if IFIS was predicted and necessary precautions taken, postoperative complications can be reduced significantly with improved visual outcome.

The Comparison of Mydriatic Effect Between Two Drugs of Different Mechanism

PURPOSE: To maximize effective use of mydriatic drugs through comparing the pupillary dilation effects between 1% tropicamide and 2.5% phenylephrine. METHODS: Fifty people requiring pupillary dilation were divided into 3 groups. Group 1 was treated with one drop of 1% tropicamide in the right eye and one drop of 2.5% phenylephrine in the left eye. Group 2 was treated twice during a 5-minute interval with 1% tropicamide in the right eye. Group 3 was treated twice during a 5-minute interval with 2.5% phenylephrine in the right eye. Groups 2 and 3 were treated with 2.5% phenylephrine and 1% tropicamide in the left eye, administered during a 5-minute interval. The pupillary size was measured in all groups for 40 minutes following eye drops administration. RESULTS: The mean patient age was 15.7 years. Group 1 included 10 patients, and groups 2 and 3 included 20 patients each. Eight patients in group 1 and 16 patients in group 2 developed a larger right pupil. Fourteen patients in group 3 developed a larger left pupil. CONCLUSIONS: Our study showed that 1% tropicamide, with its parasympathetic antagonistic mechanism of action, was more effective at inducing pupillary dilation than 2.5% phenylephrine, and the combination of 1% tropicamide and 2.5% phenylephrine was more effective than multiple drops of single eye drops.

Pupil dilation test in the diagnosis of Alzheimer's disease / 中华老年医学杂志

Objective To determine whether pupil response to dilute tropicamide could be used as a diagnostic test for Alzheimer's disease (AD). Methods Pupil diameters of both eyes were measured simultaneously by an infra red automatic pupil diameter recorder and analyzer every 0 1 second for 30 minutes after instillation of 0 01% tropicamide to one eye and normal saline to the other. Three groups of patients were studied: 52 patients with AD, 33 with vascular dementia (VD), and 58 elderly controls. The percent change in pupil diameter of the treated eye was examined automatically by the analyzer. After finding the cut off point for differential diagnosis by receiver operator characteristic curve (ROC), its sensitivity, specificity and Kappa coefficient were calculated. Results Mean percent change in diameters of the treated eye showed a trend of fastest maximum dilation in AD group, and was significantly different from other groups at all the measurement time points after 10th minute instillation. The difference was most significant at the 18th minute after instillation, and 15% was used as a cut off point, the sensitivity was 0 81,specificity 0 79 0 82, and Kappa coefficient 0 62 0 67. Conclusions Pupil dilation test could be used as a screening method in the diagnosis of Alzheimer's disease, or as a tool for differential diagnosis between AD and VD.

Pupil dilation with intracameral lidocaine during phacoemulsification / 眼科

Objective To evaluate the efficacy of mydriasis induced by intracameral injection of 1% lidocaine instead of topical mydriatics and postoperative recovery of pupil diameter in phacoemulsification surgery through a prospectively controlled clinical trial. Design Randomized clinical trial. Participants 34 patients (36 eyes) in study group,46 patients (50 eyes) in control group. Methods The study group comprised 34 patients (36 eyes),who were given intracamerally 0.5 ml unpreserved lidocaine 1% without using mydriatic eyedrops preoperatively. 46 patients (50 eyes),pupil dilated with topical mydriatics,Mydrin-p ( Tropicamid,Phenylephrine Eye Drops),were studied for comparison. As for the study group,baseline pupil diameters were recorded before the surgery,and 90 seconds after the injection of 1% lidocaine. As for the control group pupil,diameters were recorded when the surgery began. Pupil diameters at 1h,2h,4h,8h,12h,and 24h postoperatively were recorded respectively for both groups. Corneal edema and vision recovery were recorded postoperatively. Main outcome measures Pupil diameter. Results The mean baseline pupil size of the study group was 2.0611?0.1016mm,and maximum mean pupil size obtained at 90 seconds after the injection was 6.0972?0.1566mm. At the beginning of the surgery the mean pupil diameter of the control group was 7.6100?0.0799mm which was larger than 6.0972?0.1566mm (P=0.000). 75.0% eyes in the lidocaine group returned to normal size with brisk light reflex,while only 22.0% in the control group did. The time required for return to normal pupil size was significantly different between the two groups (P=0.000). Conclusions Intracameral injection of 1% unpreserved lidocaine can provide adequate pupil dilation and get rapid recovery of pupil size after surgery,though not as large as that of topical mydriatics for phacoemulsification. (Ophthalmol CHN ,2006,15: 205-208)