Significant Difference In Pupil Diameter Research Articles

Use of pupillometry for the evaluation of analgesia in dogs hospitalized in intensive care: A prospective study

A prospective study was performed on hospitalized conscious dogs. The objectives were: 1) to evaluate the feasibility and reliability of portable infrared pupillometry using a measure of photo light reflexes, 2) to identify parameters influencing measures, and 3) to compare parameters before and after the administration of analgesia.Twenty-nine dogs were included. Pupillometry was feasible by a single person. There was an excellent reliability for the evaluation of pupil diameter. There was poor to good reliability for the other parameters. There was an association between weight and mean pupil diameter (estimate = 0.1 mm, CI95 = [0.0; 0.1], P = 0.02), mean diameter variation (estimate = 0.2%, CI95 = [0.0; 0.4], P = 0.01), and mean velocity (estimate = 0.08 ms, CI95 = [0.03; 0.13], P = 0.002). Male dogs had a significantly larger mean pupil diameter than females (estimate = 1.3 mm, CI95 = [0.1; 2.5], P = 0.03). Independently of weight and sex, there was an association between mean pupil diameter and pain score: the higher the pain score, the lower the mean pupil diameter. There was a correlation between mean pupil diameter and morphine dose (ρ = −0.78, P = 0.0004). There was no significant difference in pupil diameter, velocity, and latency before and after analgesic administration.In conclusion, results do not support the use of PLR measurement by pupillometry as a pain assessment technique in hospitalized conscious dogs.

Does past/current pain change pain experience? Comparing self-reports and pupillary responses.

For decades, a substantial body of research has confirmed the subjective nature of pain. Subjectivity seems to be integrated into the concept of pain but is often confined to self-reported pain. Although it seems likely that past and current pain experiences would interact and influence subjective pain reports, the influence of these factors has not been investigated in the context of physiological pain. The current study focused on exploring the influence of past/current pain on self-reporting and pupillary responses to pain. Overall, 47 participants were divided into two groups, a 4°C-10°C group (experiencing major pain first) and a 10°C-4°C group (experiencing minor pain first), and performed cold pressor tasks (CPT) twice for 30 s each. During the two rounds of CPT, participants reported their pain intensity, and their pupillary responses were measured. Subsequently, they reappraised their pain ratings in the first CPT session. Self-reported pain showed a significant difference (4°C-10°C: p = 0.045; 10°C-4°C: p < 0.001) in the rating of cold pain stimuli in both groups, and this gap was higher in the 10°C-4°C group than in the 4°C-10°C group. In terms of pupillary response, the 4°C-10°C group exhibited a significant difference in pupil diameter, whereas this was marginally significant in the 10°C-4°C group (4°C-10°C: p < 0.001; 10°C-4°C: p = 0.062). There were no significant changes in self-reported pain after reappraisal in either group. The findings of the current study confirmed that subjective and physiological responses to pain can be altered by previous experiences of pain.

The pupil and myself: pupil dilation during retrieval of self-defining memories.

There is a recent interest in pupil dilation during the retrieval of autobiographical memory. We pursued this line of research by measuring pupil diameter during the retrieval of self-defining memories, that is, memories that are highly vivid, emotionally intense, and are retrieved to reflect enduring concerns in a person's life. We invited 40 participants to retrieve self-defining memories while their pupil activity was recorder with eye-tracking glasses. We analyzed memories regarding specificity (i.e., specific or general) and emotional valence (neutral, positive, negative, or mixed). Analysis demonstrated larger pupil diameter during the retrieval of specific than general self-defining memories. However, no significant differences in pupil diameter were observed across the four emotional categories of self-defining memories. The increased pupil size during retrieval of specific self-defining memories can be attributed to the autonoetic experience during retrieval of these memories and/or to the cognitive load as required to construct these memoires. By investigating pupil dilation during the retrieval of self-defining memories, our study provides an original, ecological, and reliable physiological assessment of these memories.

Comparison of preoperative angle kappa measurements in the eyes of cataract patients obtained from Pentacam Scheimpflug system, optical low-coherence reflectometry, and ray-tracing aberrometry

BackgroundAngle kappa plays a vital role in the implantation of multifocal intraocular lens (MIOL). Large angle kappa is related to a higher risk of postoperative photic phenomena. This study aims to compare preoperative angle kappa in the eyes of cataract patients obtained from the Pentacam Scheimpflug system (Pentacam), optical low-coherence reflectometry (Lenstar), and ray-tracing aberrometry (iTrace).MethodsOne hundred thirteen eyes of 113 patients with cataracts were included. Each eye was examined 3 times using all devices to obtain angle kappa and pupil diameter. When considering dependent eyes for one individual, angle kappa in both right eyes and left eyes should be analysed separately. The repeatability and reproducibility were evaluated using the within-subject standard deviation (Sw), repeatability (2.77 Sw), and intraclass correlation coefficient (ICC). The difference, correlation, and agreement between devices were evaluated by paired t-tests, Pearson tests, and Bland-Altman analysis, respectively.ResultsIntraoperator repeatability and interoperator and intersession reproducibility of angle kappa showed an Sw of less than 0.05 mm, a 2.77 Sw of 0.14 mm or less, and an ICC of more than 0.96. Angle kappa was not significantly different between Pentacam and Lenstar (P > 0.05), while angle kappa was significantly different between Pentacam and iTrace and between Lenstar and iTrace (P < 0.05). There was a strong correlation between Pentacam and Lenstar for angle kappa (r =0.907 to 0.918) and a weak or moderate correlation between Pentacam and iTrace and between Lenstar and iTrace (r =0.292 to 0.618). There were narrow 95% limits of agreement (LoA) between Pentacam and Lenstar for angle kappa and wide 95% LoA between Pentacam and iTrace and between Lenstar and iTrace. No significant differences in pupil diameter were found between Pentacam and Lenstar in either eye (P > 0.05). Positive angle kappa (nasal light reflex) was found in most cataract patients (79.25% to 84.91%) through 3 different devices in both eyes.ConclusionsThe 3 devices provided high intraoperator repeatability and interoperator and intersession reproducibility for angle kappa measurements. The measurement of preoperative angle kappa in the eyes of patients with cataracts by Pentacam and Lenstar has good agreement.

Evaluation and Comparison of Posterior Corneal Elevation Parameters in Different Grades of Keratoconus by Pentacam

To evaluate and compare posterior corneal elevation data and anterior segment parameters in different grades of keratoconus by Pentacam. 114 eyes of 114 keratoconic patients (85 men and 56 women) with a mean age of 31.6±4.7 years were evaluated with a Pentacam Scheimpflug camera. Keratoconic eyes were divided into 3 groups or grades according to the maximum keratometry reading: mild or grade I (K=50 or less than 50 diopters [D]), moderate or grade II (K=50.0 to 55.0 D), and severe or grade III (K=55.0 D or higher). The posterior corneal parameters were obtained posterior. There were no statistically significant differences between keratoconus grades in terms of sex (P=0.661). Also, there were no statistically significant differences between 3 grades in terms of age (P=0.214). There were statistically significant differences in anterior keratometry readings (K), anterior chamber depth (ACD), anterior chamber angle (ACA), and all pachymetric corneal measurements between all groups. With the progression of the disease, posterior K readings and all posterior elevation measurements were statistically different between the three grades. However, there were no significant differences in pupil diameter, anterior chamber volume (ACV), and corneal volume (CV) between the three grades of keratoconus. According to the results of this study, height data of posterior elevation, when combined with corneal anterior segment parameter, could provide a useful keratoconus severity classification tool.

Changes in Pupil Mydriasis as a Marker for Diabetes

Clinical Relevance: Optometrists often are the first to examine previously underdiagnosed diabetic patients because of its ocular manifestations such as a change in refractive status. This study is relevant to help optometrists identify patients with diabetes using changes in pupil mydriasis as a marker. Background: This study compared the pupillary dilatation in subjects with diabetes mellitus and those without diabetes mellitus. The purpose of the study was to use this difference as a diagnostic marker for identification of diabetes in previously undiagnosed subjects who present for eye examination. Methods: An experimental study was conducted involving 40 non-diabetic and 80 diabetic subjects with or without diabetic retinopathy. Baseline pupil diameter was measured using Orbscan and Aberrometer. Mydriasis was elicited using a combination eye drop (0.8% Tropicamide and 5% Phenylephrine). Pupil diameter was measured at 15, 30, 45 and 60 minutes after the instillation of the eye drops. The difference in pupil diameter amongst the three groups was determined using factorial ANOVA to account for the effect of age. Results: There was no significant difference between the mean pupil diameter among the three groups at baseline when measured with Orbscan (p=0.187) and Aberrometer (p=0.146). There was a significant difference in the mean and mean change in pupil diameter among the three groups with either Orbscan or Aberrometer at 30, 45 and 60 minutes after the instillation of mydriatic drops. The non-diabetics have larger pupil diameter while the diabetics with retinopathy have the least pupil diameter. Conclusion: The study showed that there was a significant difference in pupil diameter between non-diabetics, diabetics without retinopathy and diabetics with retinopathy during mydriasis. Alongside a history of symptoms of diabetes, this difference could be explored as an ocular biomarker to identify previously undiagnosed diabetes in individuals who present for routine eye examination.

Efficacy of a Cycloplegic Agent Administered as a Spray in the Pediatric Population.

To evaluate the efficacy and tolerability of cyclopentolate 1% administered as a spray in pediatric patients between 3 and 6 years old. In this prospective, randomized, parallel group study, healthy volunteers were randomly assigned to receive cyclopentolate 1% as a single drop or a single puff into closed eyes. There were 61 patients included in the study; 31 received cyclopentolate 1% as drops and 30 received cyclopentolate 1% as spray. The mean age at presentation was 4.5 ± 1.07 years (range: 3 to 6 years) and 4.2 ± 1.06 years (range: 3 to 6 years) in the drops and spray groups, respectively. The distress level was significantly lower at the time of receiving cyclopentolate as a spray (P < .0001), with the exception of patients aged 6 years. There were no significant differences in pupil diameter between the two groups (P = .51), whereas 5 of 30 patients (16.6%) with dark irises who received cyclopentolate spray did not have adequate cycloplegia to allow for accurate refraction. Cycloplegia achieved with cyclopentolate 1% administered as a spray may be an option in uncooperative children because it is less distressing compared to cyclopentolate 1% drops. However, physicians should be aware that cycloplegia obtained is only partially effective in children with dark irises. [J Pediatr Ophthalmol Strabismus. 2020;57(5):301-304.].

Pupillary response in air force and air defence pilots when exposed to Gz+ acceleration

Background/Aim. In aviation, visual functions are important for the simultaneous monitoring the instrument panel and signs in the environment. From the very beginning of the development of aviation, visual function has been deemed particularly important. The effect of +Gz acceleration on the organ of vision is very significant for investigations in aviation medicine. Visual functions are the most important of all sensory functions where flight safety and quality of flight performance are concerned. High acceleration onset rates may cause changes in pupil diameter of a pilot with significant changes in visual function. However, it is important to maintain visual functions due to rapid pilot?s orientation in the space. The aim of this study was to establish whether there was any pupillary response in Air Force and Air Defence pilots or changes in pupil diameter when exposed to +Gz acceleration in the human centrifuge. ??thods. The study was conducted on 65 Air Force and Air Defence pilots aged from 28 to 45 years of age. The pilots were exposed to an acceleration of +5.5Gz to +7Gz. We examined the obtained differences in pupil diameter according to a rate of acceleration in the period of three consecutive days. R?sults. Changes in pupil diameter during the pilot?s exposure to different high values of acceleration in the course of three days, measured before, during and after the exposure, generated statistically significant results. No statistically significant differences in pupil diameter were noticed when the pilots were exposed to the same values of acceleration before the testing on the first, second or third day. During the test, pupil diameter was statistically significantly larger than before the test. Conclusion. Transient changes in pupil diameter occurred in pilots exposed to a +7Gz acceleration. Pilots were able to withstand exposure to a +5.5Gz acceleration, without any major changes in the pupil diameter. Physiological training of pilots in the human centrifuge mimicking conditions of real G acceleration, improves tolerance to acceleration, which is important for flight safety.

Effects of prostaglandin-mediated and cholinergic-mediated miosis on morphology of the ciliary cleft region in dogs.

OBJECTIVE To compare morphology of the ciliary cleft (CC) region in dogs after topical administration of latanoprost, pilocarpine, or a combination of latanoprost and pilocarpine. ANIMALS 6 Beagles. PROCEDURES A prospective 4-phase crossover study with washout periods was performed. Latanoprost (phase L), pilocarpine (phase P), pilocarpine followed by latanoprost (phase PL), and latanoprost followed by pilocarpine (phase LP) were administered to the right eye. Artificial tears were administered to the left eye (control eye). For each phase, pupil diameter and intraocular pressure (IOP) were measured and ultrasonographic biomicroscopy was performed 2 hours after topical treatment. Angle opening distance (AOD), ciliary cleft width (CCW), ciliary cleft length (CCL), and ciliary cleft area (CCA) were evaluated. RESULTS All treated eyes had marked miosis without significant differences in pupil diameter among phases. Significant IOP reductions were detected for all phases, except phase P. The AOD and CCA were significantly increased in all phases for treated eyes, compared with results for control eyes. The CCW was significantly increased in phases P, PL, and LP; CCL was significantly increased in phases PL and LP. Comparison of treated eyes among phases revealed that CCW differed significantly between phases L and P and between phases L and PL. CONCLUSIONS AND CLINICAL RELEVANCE Prostaglandin-mediated and cholinergic-mediated miosis caused variations in CC configurations. When latanoprost and pilocarpine were used in combination, the first drug administered determined the cleft morphology, which was not fully reversed by the second drug. The CC morphology did not fully explain IOP reductions.

Is Pupil Diameter Influenced by Refractive Error?

To investigate the relationship between pupil diameter and refractive error and how refractive correction, target luminance, and accommodation modulate this relationship. Sixty emmetropic, myopic, and hyperopic subjects (age range, 18 to 35 years) viewed an illuminated target (luminance: 10, 100, 200, 400, 1000, 2000, and 4100 cd/m) within a Badal optical system, at 0 diopters (D) and -3 D vergence, with and without refractive correction. Refractive error was corrected using daily disposable contact lenses. Pupil diameter and accommodation were recorded continuously using a commercially available photorefractor. No significant difference in pupil diameter was found between the refractive groups at 0 D or -3 D target vergence, in the corrected or uncorrected conditions. As expected, pupil diameter decreased with increasing luminance. Target vergence had no significant influence on pupil diameter. In the corrected condition, at 0 D target vergence, the accommodation response was similar in all refractive groups. At -3 D target vergence, the emmetropic and myopic groups accommodated significantly more than the hyperopic group at all luminance levels. There was no correlation between accommodation response and pupil diameter or refractive error in any refractive group. In the uncorrected condition, the accommodation response was significantly greater in the hyperopic group than in the myopic group at all luminance levels, particularly for near viewing. In the hyperopic group, the accommodation response was significantly correlated with refractive error but not pupil diameter. In the myopic group, accommodation response level was not correlated with refractive error or pupil diameter. Refractive error has no influence on pupil diameter, irrespective of refractive correction or accommodative demand. This suggests that the pupil is controlled by the pupillary light reflex and is not driven by retinal blur.

Clinical analysis of pupil features in emmetropia population

目的 研究健康人不同年龄组正视眼在不同光照度下的瞳孔大小及瞳孔震颤特点.方法 收集健康志愿者120例240眼,均为正视眼,男女各半;分为21～30岁、31～40岁和41～50岁3个年龄组,每个年龄组男女各20人.应用P3000型双眼瞳孔测量仪测量各年龄组正视眼瞳孔大小及瞳孔震颤,测量分别在暗视(0.04lx)、低光照度(0.40 lx)和高光照度(4.00 lx)下进行.结果 所有受试者暗视、低光照度及高光照度下瞳孔直径的均值分别为(6.14±0.95)、(4.90±0.99)、(3.81±0.59)mm,瞳孔震颤的均值分别为0.31、0.46、0.39mm,差异均有统计学意义(瞳孔直径:F=323.78,P=0.00;瞳孔震颤:F=16.94,P=0.00).21～30岁、31～40岁和41～50岁组在3种不同光照度下瞳孔直径分别为(6.48±0.67)、(5.19±0.73)、(3.99±0.50)mm;(6.01±1.07)、(4.80±1.10)、(3.77±0.68)mm和(5.62±0.88)、(4.26±0.74)、(3.43±0.43)mm.所有受试者瞳孔直径及瞳孔震颤在不同光照度组间差异均有统计学意义.在不同光照度下不同年龄组间瞳孔直径均值差异均有统计学意义(F=13.20,P=0.00;F=14.87,P=0.00;F=13.31,P=0.00).女性受试者和男性受试者在3种不同光照度下瞳孔直径均值分别为(6.00±0.86)、(6.33±0.99)mm;(4.73±0.83)、(5.11±1.10)mm和(3.73±0.48)、(3.90±0.69)mm,除高光照度组之外,其余2组光照度下男女瞳孔直径均值差异均有统计学意义(暗视:t=-2.50,P=0.01;低光照度:t=-2.57,P=0.01;高光照度:t=-1.76,P=0.08).3种光照度下受检者双眼间瞳孔直径的差异均无统计学意义(暗视:t=0.42,P=0.68;低光照度:t=0.95,P=0.34;高光照度:t=-0.01,P=0.99).结论 瞳孔直径受光照强度、性别和年龄的影响.瞳孔震颤在3种光照度下均可发生,低光照度下更为明显。

The Effects of Systemic Alpha-1 Adrenergic Antagonists on Pupil Diameter in Rats

Purpose: To investigate the effects of alpha-1 adrenergic blockers on pupil diameter (PD) in rats. Methods: Four groups, with 10 rats each, were designed to receive terazosin, tamsulosin, doxazosin, and no medication. Dilated pupil diameter (PD) measurements were performed 24 hr before, 24 hr after, and 30 days after the initiation of medication, and after 30 days of washout. The intergroup and intragroup differences in PD were evaluated using one-way ANOVA and Wilcoxon signed rank test, respectively. Results: In day 1, PD decreased in both eyes significantly only in tamsulosin and doxazosin groups, but these effects became insignificant at 30 days of treatment (p > 0.05). The control group showed no significant difference in PD (p > 0.05). PD values returned to baseline after the washout period in all groups. Conclusions: A significant reduction in PD occurred in two of the three groups with alpha-1 adrenergic blockers (tamsulosin and doxazosin), but this effect was not sustained at 30 days. Further functional and structural studies of the iris are needed to determine the clinical significance of these findings.

Pupil dilation using a pledget sponge: a randomized controlled trial

To show that a pledget soaked in mydriatics and placed in the lower conjunctival fornix is as effective as drops in providing mydriasis for cataract surgery. A randomized, masked, controlled trial of 56 patients assigned to either a pledget group (n=25) or a control eye drops group (n=31) was carried out. Controls had the routine practice of repeated topical mydriatic drops: tropicamide, phenylepherine and atropine. The trial group had a 3-mm pledget trimmed, soaked in mydriatics and placed in the inferior fornix for 20 min. Pupil diameter was measured using a photographic technique with a standard scale shown in each picture. Two masked observers measured the pupils using the scale of the ruler in the developed photograph. All patients completed a 0-10 stinging score prior to surgery. There were no complications. The mean pupil diameter in the control group was 7.23 (6.91-7.94 95% confidence intervals [CI]) and 7.44 (6.96-7.92 95% CI) in the pledget group. There was no statistically significant difference in pupil diameter between the two groups: difference between means 0.21 (-0.32 to 0.75 95% CI) and Student's t-test of the difference between means (t=0.8 and two-tailed) probability P=0.43. There was no significant difference in the stinging scores: Mann-Whitney test P=0.69. The use of a pledget cellulose sponge to deliver mydriatics prior to cataract surgery is as effective as the conventional method of repeated drop administration and was not associated with any adverse effects.

A combination solution for routine pupillary dilation

Background This study investigated the ability of a combination drop containing reduced concentrations of tropicamide and phenylephrine to produce pupillary dilation adequate for routine fundoscopy. Methods One eye of each subject (N = 28; age range, 21 to 40 years; median, 23 years) was dilated with 1 drop of a solution containing 0.5% tropicamide and 2.5% phenylephrine (0.5T/2.5P). The other eye was dilated with 1 drop of either of 2 mixtures: 0.5% tropicamide and 1.25% phenylephrine (0.5T/1.25P, N = 15; median age, 23 years), or 0.25% tropicamide and 1.25% phenylephrine (0.25T/1.25P, N = 13; median age, 23 years). A topical anesthetic was administered before instilling the mydriatic agents. Pupil diameter was measured from a flash photograph taken every 15 minutes for 3 hours. There was no significant difference in pupil diameter between eyes dilated with the 0.5T/1.25P test solution and the 0.5T/2.5P control solution for the first 75 minutes after instillation ( P = 0.41). All pupils reached their maximum diameter 60 minutes after drop instillation; where no significant difference was observed between the 3 mydriatic solutions ( P = 0.81). All pupils were at least 7 mm in diameter 30 minutes after drop instillation, and this size was maintained for at least another 75 minutes for all solutions. Conclusions Combination preparations of reduced concentrations of tropicamide and phenylephrine can produce clinically adequate mydriasis.

Evaluation of a new preoperative ophthalmic solution

Background: Maximum mydriasis and corneal clarity during intraocular surgery are important to ensure operational safety. However, repeated instillation of mydriatic and anti-inflammatory ophthalmic solutions during surgery may affect compliance and may damage the corneal epithelium.We developed an ophthalmic solution containing tropicamide, phenylephrine hydrochloride and diclofenac sodium, and compared the properties and effect on corneal epithelial barrier function and on mydri-asis of the solution and of its individual components.Methods: We developed the ophthalmic solution by mixing 10 mL of 0.5% tropi-camide/0.5% phenylephrine, 10 mL of 5% phenylephrine and 10 mL of 0.1% diclofenac (TPD). We determined the stability of the chemicals in solution using high-performance liquid chromatography immediately, 1 week and 1 month after mixing. Corneal epithelial barrier function was assessed before and after instillation of the solutions in 26 eyes of 17 patients (5 with proliferative diabetic retinopathy or diabetic maculopathy, 8 with cataract and 4 with no eye disease).The fluorescent intensity was measured 10 times at the central cornea 30 minutes after instillation of 3 mL of 0.5% fluorescein solution and the average value calculated. Finally, the pupil diameter of 50 eyes of 38 patients undergoing cataract surgery was measured before and immediately after the operation.Results: No remarkable changes in the pH or pharmacologic activity of the TPD solution were observed at any time after mixing. In the patients with diabetic retinopathy or cataract, the increase in mean fluorescent intensity was significantly greater with the individual solutions than with the TPD solution (p < 0.01); there was no significant difference in mean fluorescent intensity in the subjects with no eye disease. No statistically significant difference in pupil diameter was observed between the eyes that received the TPD solution and those that received the individual solutions.Interpretation:TPD ophthalmic solution is simple to prepare and use.The TPD solution had a similar effect on mydriasis as the three individual solutions but was less destructive to the corneal epithelium.

The effect of latanoprost 0.005% on pupillary reaction of the human eye

Infrared pupillography was performed to investigate the effect of one week topical treatment with the prostaglandin analogue Latanoprost 0.005% on pupillary reflex to light stimuli in glaucomatous human eyes. Infrared pupillography using the compact integrated pupillograph was performed in 20 glaucomatous eyes of 11 patients. After 10 minutes dark adaptation one pupil was stimulated with a blue, yellow and white diode light of 100 ms duration. Measurements of pupil diameter, constriction latency, constriction amplitude and relative constriction amplitude were taken twice for each light source in a time interval of 15 seconds. After a 2 week wash-out period the measurements were performed from 8:00 to 10:00 a.m. before and one week after topical treatment with Latanoprost 0.005% applied as single dose once in the evening. The measurements after 1 week treatment with Latanoprost showed a significantly smaller pupil diameter for blue (p = 0.044) and white stimulus (p = 0.039) and the latency was significantly reduced (p = 0.029) as well. Although the statistical analysis shows some small significant differences in pupil diameter and constriction latency there were no clinical signs of changes in pupillary response due to Latanoprost. The system turned out as easy to use and showed reliable measurements during the study. How far latanoprost may lead to miosis and a decrease of constriction latency has to be investigated in further studies with larger study populations. Other topics concerning drug influence, diurnal rhythm and glaucomatous damage in pupillary light reaction will be investigated in the near future.