Phenol Red Thread Research Articles

Ocular parameters in a captive colony of fruit bats

To establish normal reference ranges of ocular parameters including phenol read thread, palpebral fissure length, horizontal and vertical corneal diameter, upright and hanging intraocular pressure (IOP) and to report ophthalmic examination findings of the anterior segment and lens, in a population of captive fruit bats. Eyes of 30 bats of three species were included in this study: 10 (5 males, 5 females) Malayan Flying Foxes (Pteropus vampyrus), 10 (5 males, 5 females) Little Golden-mantled Flying Foxes (Pteropus pumilus), and 10 (4 males, 6 females) Island Flying Foxes (Pteropus hypomelanus). The most common ophthalmic examination findings included iris-iris persistent pupillary membranes (83%), nuclear sclerosis (56.7%), prominent arterial circle (40%), iridal hyperpigmented foci (30%), pupillary margin cysts (27%), and third eyelid defects (20%). The mean, among all species for: phenol red thread was 20.23 ± 1.28 mm/15 s both eyes (OU); palpebral fissure length was 13.34 ± 0.33 mm for OU; for horizontal corneal diameter was 10.72 ± 0.32 mm for OU; for vertical corneal diameter was 9.90 ± 0.30 mm for OU; for the hanging intraocular pressures was 19.38 ± 0.77 mmHg for OU; for upright IOP was 13.95 ± 0.60 mmHg for OU. Measurements for the individual species groups and eyes were also calculated. Results revealed the IOP of bats in a hanging position were significantly higher than the IOP of bats in an upright position. The size of the bat, between the species, affected palpebral fissure length, horizontal corneal diameter, and vertical corneal diameter. Information about the ocular structures and normal ophthalmic parameters for the Pteropus species is crucial for species protection because of dependence on vision for survival.

Use of Phenol Red Thread Test as a rescue test in diagnostic strategy of severe ocular syndrome

Abstract Purpose To define a combination between Schirmer I and phenol red thread test (PRT) that improves the screening of patients with ocular sicca syndrome. Methods The PRT test was performed before (PRT1) and after (PRT2) the Schirmer I test, in both eyes of 143 patients complaining of ocular dryness secondary to Sjögren’s syndrome (SGS) or Sicca Asthenia Polyalgia Syndrome (SAPS) (72 and 71 patients respectively), and in 40 patients with no sign of dry eye. Groups were matched by age and gender. After determining the best cut‐off values using the ROC procedure, several combinations of PRT and Schirmer I were assessed to improve the predictive values of the procedure. Results The best cut‐off value for PRT2, estimated at 15mm, provided a satisfying match between sensitivity and specificity indexes (68% and 90% respectively), similar to those obtained with the Schirmer I test. If PRT1 alone was ineffective to screen SGS from control patients, the comparison between PRT 1 and PRT2 (”delta‐PRT”) was found as a good marker to detect patients with persistent tear reflex. The combination of positive Schirmer I, PRT 2 and/or delta‐PRT tests was found as highly predictive of severe ocular sicca syndrome. Conclusion The combination of Schirmer I and PRT test improves the screening procedure to detect patients with severe ocular dryness. Since PRT test is non‐invasive and time‐effective, it could be more widely used in daily clinical practice, besides Shirmer I test, to optimize the work‐up of patients presenting with dry‐eye subjective signs.

Reference values for selected ophthalmic diagnostic tests and clinical characteristics of chinchilla eyes (Chinchilla lanigera)

To establish reference values for the Schirmer tear test I (STT I), the phenol red thread tear test (PRTT), the intraocular pressure (IOP) with rebound tonometry, to determine the corneal sensitivity for healthy chinchillas, and to describe clinical aspects of normal chinchilla eyes. One hundred and twenty-two eyes of 61 healthy pet chinchillas of different age and gender were investigated. A full ophthalmic exam including slit lamp biomicroscopy, ophthalmoscopy, measurement of STT I, PRTT, determination of the corneal touch threshold (CTT), and the measurement of the IOP (TonoVet) was performed. The normal appearance of the lid, the iris, the lens, the fundus, and the optic nerve disc was evaluated. Results The results of the STT I were very low and not reliable, and the measurement was discontinued. The median value of PRTT was 14.0 mm wetting/15 s (mean 14.6 ± 3.5 mm wetting/15 s). The median CTT was 32.5 mm (mean 31.2 ± 7.0 mm) respectively 1.2 g/mm(2) (mean 1.5 ± 0.9 g/mm(2)). The median IOP was 3.0 mmHg (mean 2.9 ± 1.8 mmHg). The predominating iris color was brown. The fundus pigmentation varied. Few lens alteration were seen in otherwise healthy chinchilla eyes. Most chinchillas had myelinated discs. Optic nerve cupping was present in 62% of the animals. Because of the small amount of tears, the PRT test is recommended for tear measurements in chinchillas. The IOP in chinchillas seems to be quiet is low in comparison to other rodents.

Measurement of phenol red thread tear test in Arabian and throughbred horses

To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT). The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey. For the measurement of PRT, the strip was placed under the lower eyelid approximately one-third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides. The mean length of the wet area was in AH and TH were 30.22 +/- 0.99 mm ranging from 16 to 41 and 31.00 +/- 1.4 mm ranging from 14 to 47, respectively. There were no significant differences in tear production among breed, sex, or age groups. The values measured for left eyes were significantly higher than those for right eyes (P < 0.05). Phenol red thread test measurement is easily used, with no pain, and a comfortable method. PRT can be used in equine ophthalmology on a routine basis to the measurement of tear production. These normal PRT values help diagnosis keratoconjunctivitis sicca in horses.

Tear lipocalin and lysozyme concentrations in postmenopausal women

To investigate the potential relationship between subjective symptomatology, tear volume, and tear break up time with tear film lipocalin and lysozyme concentrations in a group of symptomatic dry-eyed postmenopausal (PM) women compared to age-matched controls. Eighty-five healthy PM females (>50 years of age) were categorized as mild or moderate dry eye (DE), or asymptomatic [non-dry eye (NDE)] based on their responses to the Ocular Surface Disease Index (OSDI) questionnaire. Non invasive tear breakup time (NITBUT) and tear secretion were measured. Tears were collected via capillary tube and an eye wash method. Tear lysozyme and lipocalin concentrations were determined via Western blotting. Ocular Surface Disease Index responses revealed 16 mild DE, 30 moderate DE, and 39 NDE. The OSDI total score and sub scores for the DE groups were significantly greater than for the NDE group (p < 0.001). The mild and moderate DE groups exhibited significantly shorter NITBUTs compared to NDE (p < 0.004). Tear secretion using the Phenol Red Thread (PRT) test was found to be significantly lower in the moderate DE group compared to NDE (p < 0.001). No difference in tear lysozyme or lipocalin concentration was found between DE and NDE groups, irrespective of tear collection method, although method of collection significantly influenced absolute concentrations (p < 0.008). Significant correlations were not found between symptoms or signs of DE compared to either lipocalin or lysozyme concentration. Within a PM population, lipocalin and lysozyme are invariant, irrespective of the presence and severity of DE symptoms. This is the first comprehensive study of lipocalin and lysozyme in dry-eyed PM women and our results suggest that neither protein would offer utility as a biomarker of DE.

Use of phenol red thread tests to evaluate tear production in clinically normal Amazon parrots and comparison with Schirmer tear test findings

To determine phenol red thread test (PRTT) values in eyes of clinically normal Hispaniolan Amazon parrots before and after topical application of an ophthalmic anesthetic agent and compare findings with Schirmer tear test (STT) values. Evaluation study. 24 Amazona ventralis parrots from a research colony. On 4 occasions (1-week intervals), all birds underwent a thorough ophthalmic examination of both eyes, which included (in sequence) performance of a PRTT and an STT; topical ocular application of proparacaine hydrochloride; and performance of another PRTT and another STT. Correlations between PRTT and STT values recorded with and without topical anesthesia were assessed. Without topical anesthesia, mean +/- SD PRTT value was 12.5 +/- 5.0 mm/15 s (range, 1 to 25 mm/15 s). With topical anesthesia, the PRTT value was 12.6 +/- 5.4 mm/15 s (range, 2 to 24 mm/15 s). Without topical anesthesia, mean STT value was 7.9 +/- 2.6 mm/min (range, 0 to 13 mm/min). With topical anesthesia, the STT value was 5.1 +/- 3.3 mm/min (range, 0 to 18 mm/min). The correlation of PRTT and STT values recorded with or without topical anesthesia was weak (r = 0.51 and r = 0.32, respectively). Results indicated that the PRTT and STT were both viable methods for measurement of tear production in Hispaniolan Amazon parrots. Topical application of an ophthalmic anesthetic agent did not have a significant effect on the PRTT values but significantly decreased the STT values.

Sjögren’s Syndrome-Like Ocular Surface Disease in Thrombospondin-1 Deficient Mice

Thrombospondin-1 (TSP-1) is a major activator of latent transforming growth factor-beta in vitro as well as in vivo. Mice deficient in TSP-1, despite appearing normal at birth, develop a chronic form of ocular surface disease that is marked by increased apoptosis and deterioration in the lacrimal gland, associated dysfunction, and development of inflammatory infiltrates that result in abnormal tears. The increase in CD4(+) T cells in the inflammatory infiltrates of the lacrimal gland, and the presence of anti-Sjögren's syndrome antigen A and anti-Sjögren's syndrome antigen B antibodies in the serum resemble autoimmune Sjögren's syndrome. These mice develop an ocular surface disorder dry eye that includes disruption of the corneal epithelial layer, corneal edema, and a significant decline in conjuctival goblet cells. Externally, several mice develop dry crusty eyes that eventually close. The inflammatory CD4(+) T cells detected in the lacrimal gland, as well as those in the periphery of older TSP-1 null mice, secrete interleukin-17A, a cytokine associated with chronic inflammatory diseases. Antigen-presenting cells, derived from TSP-1 null, but not from wild-type mice, activate T cells to promote the Th17 response. Together, these results indicate that TSP-1 deficiency results in a spontaneous form of chronic dry eye and aberrant histopathology associated with Sjögren's syndrome.

A Novel Method to Predict the Dry Eye Symptoms in New Contact Lens Wearers

Lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOF) give moderate prediction levels for dryness symptoms in experienced contact lens (CL) wearers. This study investigated whether a combination of LWE and LIPCOF plus other tear film tests and subjective evaluation before contact lens fitting was better able to predict CL-induced dry eye (CLIDE) symptoms. Tear meniscus height, non-invasive break-up time (NIBUT), ocular hyperaemia, LIPCOF, phenol red thread test, corneal and conjunctival staining, and LWE of the right eye of 33 new soft CL wearers (12 males, 21 females, median age = 30.5 years; range = 19 to 44) were assessed in a prospective 2-mo longitudinal study. Symptoms were evaluated by the Ocular Surface Disease Index (OSDI) and subjects were grouped according to their response in the Contact Lens Dry Eye Questionnaire (CLDEQ) during the study (20 symptomatic and 13 asymptomatic). The subjects were fitted with vifilcon A and senofilcon A lenses for a 2-week period, consecutively. Limbal hyperaemia (repeated measures analysis of variance; p < 0.05) and LWE (Friedman; p < 0.004) increased significantly during the study but not LIPCOF (p > or = 0.318; temporal, nasal, and Sum), bulbar hyperaemia (p = 0.432), staining (p > or = 0.060), OSDI (p = 0.126), or CLDEQ (p = 0.317, kappa = 0.279). Limbal hyperaemia significantly decreased in senofilcon A lenses. Wearing comfort among symptomatics was significantly better with senofilcon A (p = 0.005). At the enrolment visit, the subjects who became symptomatic exhibited significantly decreased NIBUT and increased LIPCOF and OSDI (range, p < 0.027). The best test combination to predict CLIDE (logistic regression analyses) was LIPCOF Sum plus NIBUT and OSDI, (positive predictive value = 87% and accuracy = 91%). LIPCOF, NIBUT, and OSDI are significant discriminators for CLIDE in new CL wearers compared with hyperaemia, tear meniscus height, phenol red thread test, staining, and LWE. The best test combination is NIBUT plus LIPCOF Sum and OSDI (named the Contact-Lens-Predicting-Test).

The effectiveness of questionnaires in the determination of Contact Lens Induced Dry Eye

This study investigates how well the recently introduced Ocular Comfort Index (OCI) and the more established McMonnies Dry Eye Index are able to detect contact lens induced dry eye (CLIDE). Seventy volunteer contact lens wearers (mean age = 28.7 +/- 8.0; 52 female, 18 male) were grouped as CLIDE positive or CLIDE negative depending on three sets of criteria: Method I: objective (tear meniscus height, lid parallel conjunctival folds, phenol red thread test and tear break-up time); Method II: objective and/or subjective [contact lens dry eye questionnaire (CLDEQ)] (i.e. being positive by Method I and/or Method III); Method III: subjective (CLDEQ). Symptoms were measured using the McMonnies Dry Eye Index and the OCI. Discrimination was analysed by the receiver operating characteristic (ROC) curves; positive predictive values (PPV) and cut-off values were calculated. ROC results for Methods I and II were statistically significant only for the McMonnies (p = 0.008; p < 0.001; respectively). In Method III ROC results were statistically significant for both the McMonnies (p = 0.001) and OCI (p = 0.005). The McMonnies showed the best prediction of Method I [0.646/10.5 (PPV/cut-off value)], while the OCI gave the best predictability in Method III only (0.518/30.6). A McMonnies scoring of > or = 10.5 or an OCI scoring of > or = 30.6 indicates CLIDE. The McMonnies performs better in prediction of CLIDE than the OCI.

Survey of Oculoplastic Surgeons Regarding Clinical Use of Tear Production Tests

To determine by a survey of ophthalmic plastic surgeons with specific expertise in blepharoplasty surgery the perceived role of Schirmer testing and other evaluation features in determining patient predisposition to postoperative dry-eye complaints. A literature review of tear production tests was performed. An anonymous survey was mailed to all members of the American Society of Ophthalmic Plastic and Reconstructive Surgery. The survey included questions on practice patterns, the role of different objective tests, and the occurrence of postblepharoplasty dry-eye or exposure complaints. Forty-eight percent (263 of 544) of those surveyed responded. All responding physicians perform a clinical history and examination to preoperatively evaluate for dry eye, 36% perform no additional tear production tests, 33% perform a test if indicated by signs or symptoms, 29% always perform a test, and 1% perform a test only if multiple procedures were planned. Schirmer testing with anesthetic is the predominant test used by physicians who perform tear production tests (89%), followed by Schirmer test without anesthetic (10%), and phenol red thread test (1%). Nevertheless, 74% of physicians felt that Schirmer testing should not be a medical standard of care in evaluating blepharoplasty patients. The preoperative evaluation of blepharoplasty patients may be severely limited in specialties that perform Schirmer testing or other tear production tests without the benefit of a directed clinical history and slit lamp examination. Current tear production tests are unreliable in detecting dry eye. The ideal approach to the evaluation of the blepharoplasty patient remains controversial.

The effect of soft contact lens wear and time from blink on wavefront aberration measurement variation

Introduction: Advances in contact lens design technology allow incorporation of correction of higher‐order aberrations to improve or manipulate the eye's optical quality. Repeatability of aberration measurements in vivo with contact lens wear has not been established.Method: Higher‐order aberrations were measured using the COAS aberrometer (Wavefront Sciences, USA) in 23 participants who were free from external eye pathology. Cycloplegia with 1% Cyclopentolate HCl ensured control of accommodation and that pupil diameters exceeded analysis diameter. Tear film characteristics were assessed with the phenol red thread test and Keeler Tearscope. Variability in wavefront aberrations was assessed with and without a low powered soft contact lens. The effect of time after the blink and tear film characteristics were also investigated.Results: Standard deviations differed significantly for some fifth‐order terms (p ≤ 0.003) with contact lens wear. Coefficient of variation did not increase significantly with contact lens wear. Time from blink increased standard deviations in the third‐order (p ≤ 0.003). The effect of contact lens wear and time from blink differed between groups with different tear film characteristics.Conclusions: Variability in measurements of aberrations increased significantly for odd‐order aberrations when a contact lens was worn or between blinks. Fourth‐order aberrations showed less effect of contact lens wear. Therefore, verification of the performance of lenses with aspheric optics on eye is feasible. Accurate assessment of higher‐order aberrations is more difficult when a contact lens is worn. Both contact lens wear and time from blink increase variability in aberrations, which suggests a role for the tear film in increased aberrations with soft contact lens wear.

Selecting highly sensitive non-obese diabetic mice for improving the study of Sjögren’s syndrome

Non-obese diabetic (NOD) mice are a commonly used murine model for the study of Sjögren's syndrome. However, variations in susceptibility to the disease among the mice has often yielded less stable results. Based on the correlation between the pathological changes and the tear tests, we attempt to establish a simple screening procedure to assure the validity of experimental results by excluding those mice with poor susceptibility to dry eyes. Seventy male NOD mice were recruited. The tear film break-up test (BUT) and the phenol red cotton thread test (CTT) were implemented while the mice were under anesthesia. The mice were divided into four groups (grades 1 to 4) based on their BUT readings, and four similar groups based on CTT measurements. Tear samples in each grade were collected for IL-1beta detection with ELISA. The lacrimal glands and conjunctiva of the mice were used to detect the levels of leucocyte common antigen (LCA). LCA-Positive staining was considered as the "gold standard" in the receiver operating characteristic curve (ROC curve) analysis. C57BL/6 mice were used as wild-type controls. There were 13 (18.57%), 43 (61.43%), 10 (14.29%) and 4 (5.71%) mice in grades 1, 2, 3 and 4 by BUT test, and 34 (48.57%), 15 (21.43%), 14 (20.00%) and 7 (10.00%) in grades 1, 2, 3 and 4 by CTT test respectively. Fifty-one out of the 70 mice (72.86%) were detected LCA-positive, and they were mainly in grades 1 and 2 of both the BUT and CCT grading systems. ELISA showed significant variances of IL-beta levels among the four groups (p < 0.01), with much lower IL-beta levels in group 3 and 4 when both BUT and CTT were used for grouping. The tear IL-beta level in the wild-type mice was similar to those of the grade 4 mice, using either BUT or CTT for grouping. The ROC curve analysis provided optimal cutting lines, which were 2 seconds in BUT readings and 4 mm/min in CTT measurements respectively. BUT and CTT tests are useful methods in screening high susceptible NOD mice. Cutting lines at BUT < or = 2 seconds and CTT < or = 4 mm/min provide a good balance between the assurance of susceptibility and the maximization of use of NOD mice for the study of Sjögren's syndrome.

Concordance between common dry eye diagnostic tests

Aim:Large variations in results of diagnostic tests for mild to moderate dry eye are widely recognised. The purpose of this study was to assess if there was concordance between common...

Topical Apolipoprotein A-1 May Have a Beneficial Effect on the Corneal Epithelium in a Mouse Model of Dry Eye: A Pilot Study

Dry-eye syndrome affects millions of individuals and it is essential to develop effective therapeutic agents for the treatment of this complex condition. The goal of this study was to evaluate the effect of apolipoprotein A (ApoA)-1 and its synergistic action with d-pantethine (DP) on corneal epithelial disorders in dry-eye mouse model. Aqueous tear production of C57BL/6J Jms Slc male mice aged 10 to 12 weeks were inhibited by subcutaneous scopolamine injection and mice were placed in a continuous airflow blower to create desiccating environmental stress. During desiccation, 1 eye of each mouse was treated with ApoA-1 (0.01%, 0.04%, or 0.1%) or ApoA-1 (0.04%) + DP (0.05%, 0.1%, or 0.2%) and the other control eye was instilled with phosphate-buffered saline 4 times daily for 5 days. Phenol red thread test, corneal fluorescein staining (score, 0-4), and measurement of corneal epithelial thickness measurements were performed. Significant reductions of staining scores and higher corneal epithelial thickness values were observed in both ApoA-1- and ApoA-1 + DP-treated groups compared with untreated dry-eye mouse and phosphate-buffered saline-treated group. These results suggest that ApoA-1 and DP may be potential therapeutic agents for ocular surface epithelial disorders in patients with dry eye.

Optimisation of diagnostic strategy in severe ocular sicca syndrome

Abstract Purpose To define the interest of phenol red thread in diagnosis of ocular sicca syndrome, and to estimate the agreement with the Schirmer I test. Methods The PRT test was performed before (PRT1) and after (PRT2) the Schirmer I test, in both eyes of 72 patients complaining of ocular dryness secondary to Sjögren’s syndrome, 71 patients with Sicca Asthenia Polyalgia Syndrome and 40 healthy volunteers. Only the lowest result for each test was used in statistical analysis and cut‐off values were determined using the Receiver Operating Curve procedure. Groups were matched by age and sex. Results The ROC procedure showed weak sensitivity/specificity couples whatever PRT1 cut‐off value. A cut‐off value of 15mm for PRT2 provided the best ratio between sensitivity and specificity (68% and 90% respectively) and 10mm for Schirmer I test permitted a sensitivity of 77.80% and specificity of 82.50%. Maximal agreement between PRT2 and Schirmer I test was found for a PRT2 value of 15mm with however a mean agreement (Kappa index~ 0.5); however none of PRT2 test alone or Schirmer I test alone was better than the other for diagnosis of ocular sicca syndrome. In contrast, the combination of Schirmer I test (≤10mm), PRT2 test (≤15mm) and negative“deltaPRT” (PRT2 &lt; PRT1) permitted to increase sensitivity and specificity to 92% and 95%, respectively. Conclusion Schirmer I test must certainly be used firstable in diagnostic step. However PRT2 and negative « deltaPRT » permit classification of patients « forgotten » by Schirmer I test. Finally, association Schirmer I test, PRT2 and negative « deltaPRT » offers characteristics of diagnostic test (high specificity (90%) and sensitivity (85%)) with a high positive predictive value (73, 3%) for SGS.

Clinical signs and symptoms in post‐menopausal females with symptoms of dry eye

To characterize clinical signs and symptoms in a group of post-menopausal (PM) females who present with and without symptoms of dry eye. Eighty-three healthy PM females were categorized as being symptomatic or asymptomatic of dry eye based on their response to the Allergan Ocular Surface Disease Index (OSDI) questionnaire. Non-invasive tear breakup time (NITBUT) was evaluated using the ALCON Eyemap. Tear volume was assessed using the phenol red thread (PRT) test and bulbar conjunctival hyperaemia was measured using objective and subjective methods. The total OSDI score (TOS) and subscores for the non-dry eye (NDE; n = 39) and dry eye (DE; n = 44) groups were significantly different (TOS: NDE = 7.43 +/- 7.71 vs DE = 24.87 +/- 13.89; p < 0.001). The DE group exhibited a shorter NITBUT (5.3 +/- 1.7 s vs 7.0 +/- 2.7 s; p = 0.0012). Tear volume was lower for the DE group (19.3 +/- 5.1 mm vs 16.3 +/- 5.6 mm; p = 0.031). Bulbar hyperaemia was higher in the DE group for both subjective grading using a modified CCLRU scale (48.4 +/- 10.0 vs 40.6 +/- 10.4; p = 0.0011) and objective measurement by spectrophotometer (Commission Internationale de l'Eclairage u' value = 0.285 +/- 0.006 vs 0.282 +/- 0.006; p = 0.005). OSDI can be used to separate PM females who demonstrate clinical signs of ocular dryness. PM women with dry eye symptoms demonstrate shorter NITBUT, lower tear volume and increased bulbar conjunctival hyperaemia than those who have no symptoms.

Results of diagnostic ophthalmic testing in healthy guinea pigs

OBJECTIVE-To report values for tear production, central corneal touch threshold (CTT), and intraocular pressure (IOP) in healthy guinea pigs and determine results of aerobic bacterial culture and cytologic examination of conjunctival swab specimens. DESIGN-Cross-sectional study. ANIMALS-31 Healthy guinea pigs (62 eyes) of various ages and breeds. PROCEDURES-Tear production was measured by the phenol red thread tear test (PRT) and Schirmer tear test (STT) before and after topical anesthetic application, CTT was measured with an esthesiometer, and IOP was measured by applanation tonometry. RESULTS-Combining data from all eyes, mean +/- SD PRT values before and after topical anesthetic administration were 21.26 +/- 4.19 mm/15 s and 22.47 +/- 3.31 mm/15 s, respectively, and mean IOP was 18.27 +/- 4.55 mm Hg. Median STT values before and after topical anesthetic administration were 3 mm/min (range, 0 to 12 mm/min) and 4 mm/min (range, 0 to 11 mm/min), respectively, and median CTT was 2.0 cm (range, 0.5 to 3.0 cm). Values did not differ between eyes for any test, but significant differences were identified for PRT values between males and females and between values obtained before and after topical anesthetic administration. Common bacterial isolates included Corynebacterium spp, Streptococcus spp, and Staphylococcus spp. Cytologic examination of conjunctival swab specimens revealed mainly basal epithelial cells; lymphocytes were common. CONCLUSIONS AND CLINICAL RELEVANCE-Results provided information on values for PRT, STT, CTT, and IOP in healthy guinea pigs and on expected findings for aerobic bacterial culture and cytologic examination of conjunctival swab specimens.

Ophthalmic examination findings in a colony of Screech owls (Megascops asio)

To report ophthalmic findings in the Screech owl (Megascops asio). Sample population Twenty-three, apparently healthy adult captive Screech owls in Maryland. OU of all owls underwent complete ophthalmic examination. One randomly assigned eye of each bird was measured by phenol red thread tear test (PRT), and the other eye by Schirmer tear test (STT). TonoVet rebound tonometry and TonoPen-XL applanation tonometry were performed in each eye to measure IOP. Conjunctival swabs were cultured from one eye of 10 birds, corneal diameter was measured in OU of eight birds, and streak retinoscopy was performed on OU of seven birds. Ten birds were anesthetized, and A-scan ultrasonography using a 15-MHz probe was performed to obtain axial intraocular measurements. Ophthalmic abnormalities were noted in 24/46 (52%) of eyes. Median STT result was < or = 2 mm/min, ranging < or = 2-6 mm/min, and mean +/- SD PRT was 15 +/- 4.3 mm/15 s. Mean +/- SD IOP were 9 +/- 1.8 mmHg TonoVet-P, 14 +/- 2.4 mmHg TonoVet-D, and 11 +/- 1.9 mmHg TonoPen-XL. Coagulase negative staphylococcal organisms were cultured from all conjunctival swabs. Mean +/- SD corneal dimensions were 14.5 +/- 0.5 mm vertically and 15.25 +/- 0.5 mm horizontally. All refracted birds were within one diopter of emmetropia. Mean +/- SD axial distance from the cornea to the anterior lens capsule was 4.03 +/- 0.3 mm, from cornea to the posterior lens capsule was 10.8 +/- 0.5 mm, and from cornea to sclera was 20.33 +/- 0.6 mm. This study reports ophthalmic examination findings in Screech owls, and provide means and ranges for various ocular measurements. This is the first report of rebound tonometry and PRT in owls.

Conjunctival and Corneal Pneumatic Sensitivity Is Associated with Signs and Symptoms of Ocular Dryness

To investigate the relationships of dry eye symptoms and corneal and conjunctival sensitivity to pneumatic stimulation, tear film stability, and clinical ocular surface characteristics in symptomatic and asymptomatic subjects. Ninety-seven subjects were enrolled and grouped by a questionnaire-based single score for symptoms of ocular dryness (none to trace, non-dry group; mild to severe, symptomatic group); 43 were symptomatic and 54 were non-dry. Corneal (K) and conjunctival (C) sensitivities were measured with a computer-controlled Belmonte pneumatic (room temperature) stimulus. Symptoms were assessed according to the Ocular Surface Disease Index (OSDI). Ocular surface staining with fluorescein (FL) and lissamine green (LG), noninvasive tear film break-up time (NIBUT), and the phenol red thread test (PRT) were assessed. The symptomatic group showed lower K and C thresholds (P < 0.01), greater corneal FL and conjunctival LG staining, and shorter NIBUT than did the non-dry eye group (all others P < 0.05). The OSDI scores were higher in the symptomatic group (P < 0.001). K and C thresholds and NIBUT were inversely correlated with the OSDI and corneal and conjunctival staining (all P < 0.05). The K and C threshold and NIBUT (all P < 0.01) correlated positively. Step-wise multiple regression analysis showed that ocular surface sensitivity and NIBUT were significant predictors of the OSDI. Ocular irritation assessed with the OSDI is associated with ocular surface hyperesthesia to cooling, corneal epitheliopathy, and tear film instability. Although cause and effect are unclear, the analysis showed that altered corneal and conjunctival sensory processing and tear film attributes are essential aspects of what characterizes dry eye.

Quantitative assessment of tear production: A review of methods and utility in dry eye drug discovery.

The successful development of a therapeutic agent targeting treatment of dry eye syndrome necessitates the demonstration of drug efficacy for both sign and symptom endpoints. As numerous therapeutic strategies incorporate a secretagogue function into their overall mechanism of action, the quantitative assessment of tear production serves as a logical endpoint to anchor “sign” efficacy. Although several methods including the Schirmer, the phenol red thread and tear clearance tests exist, their utility in clinical evaluations of novel therapeutics is unclear. The purpose of this review is to summarize findings and conclusions describing the performance of each of these tests so as to gain insight into which, if any, is most applicable for use in discovering new dry eye therapeutics.