Long term observation of ocular surface alkali burn in rabbit models: Quantitative analysis of corneal haze, vascularity and self-recovery.

Limbal Stem Cell Deficiency (LSCD), caused due to corneal injury, primarily by chemical/alkali burns, leads to compromised vision. Recently, several animal models of corneal alkali burn injury have become available. The majority of the studies with these animal models start interventions soon after the injury. However, in the clinical setting, there is a considerable delay before the intervention is initiated. Detailed knowledge of the molecular, histopathological, and clinical parameters associated with the progression of the injury leading to LSCD is highly desirable. In this context, we set out to investigate clinical, histopathological parameters of ocular surface alkali burn over a long period of time, post-injury. Limbal stem cell-deficient animal models of rabbits were created by alkali burn using sodium hydroxide, which was then assessed for their progression towards LSCD by grading the alkali burn, corneal haze, and vascularization. Additionally, cells present on the corneal surface after the burn was investigated by histology and immunophenotyping. Grading of rabbit eyes post-alkali burn had shown complete conjunctivalization in 80% (n = 12/15) of the rabbits with the alkali burn grade score of 3.88 ± 0.29 in three months and remained stable at four months (4.12 ± 0.24). However, ocular surface showed self-healing in 20% (n = 3/15) of the rabbits with a score of 1.67 ± 0.34 in four months irrespective of similar alkali injury. These self-healing corneas exhibited decreased opacity score from 2.51 ± 0.39 to 0.66 ± 0.22 (p = 0.002) and regressed vascularity from 1.66 ± 0.41 to 0.66 ± 0.33 in one to nine months, respectively. Restoration of the corneal phenotype (CK3+) was observed in central and mid-peripheral regions of the self-healing corneas, and histology revealed the localization of inflammatory cells to the peripheral cornea when compared to conjunctivalized and scarred LSCD eyes. Our study shows the essentiality to consider the time required for surgical intervention after the corneal alkali injury in rabbit models as evident from their tendency to self-heal and restore corneal phenotype without therapy. Such information on the possibility of self-healing should be useful in further studies as well as determining interventional timings and strategy during clinical presentation of corneal alkali burns.

Conjunctival microcirculation is associated with cerebral cortex microcirculation in post-resuscitation mild hypothermia: A rat model.

OBJECTIVE: This study aimed to compare the changes in sublingual and conjunctival microcirculation occurring with cerebral cortex microcirculation changes during mild hypothermia in a rat model of cardiac arrest. METHODS: Twenty-four rats were randomized into mild hypothermia (M) or normothermia (C) groups. Ventricular fibrillation was electrically induced and left untreated for 8 minutes, followed by 8 minutes of cardiopulmonary resuscitation. The core temperature in group M reduced to 33 ± 0.5°C at 13 minutes after restoration of spontaneous circulation and was maintained for 8 hours. In group C, the core temperature was maintained at 37 ± 0.2°C. The hemodynamics and microcirculation in the sublingual region, bulbar conjunctiva, and cerebral cortex were measured at baseline and 1, 2, 3, 4, 6, and 8 hours after restoration of spontaneous circulation. RESULTS: The M group showed significantly worse sublingual microcirculation at 6 hours post-resuscitation. However, microcirculation in the conjunctiva and cerebral cortex at 3 hours post-resuscitation were better in the M group. In the M group, microcirculation in the cerebral cortex was significantly correlated with that in the conjunctiva but not the sublingual microcirculation. CONCLUSIONS: Changes in conjunctival microcirculation are closely related to cerebral cortex microcirculation during mild hypothermia, indicating that cerebral cortex microcirculation could be monitored by measuring conjunctival microcirculation.

Topical Review: Effects of Contact Lens Wear on Corneal, Conjunctival, and Lid Margin Sensitivity.

SIGNIFICANCE: Contemporary soft contact lenses do not affect mechanical sensitivity of the cornea, whereas conjunctival sensitivity is increased compared with nonwearers. Orthokeratology lens wear, however, reduces corneal sensitivity. The effects of contact lenses on lid margin sensitivity are unclear, and the link between ocular surface sensitivity and discomfort requires further exploration.Although up to 50% of contact lens wearers experience discomfort with varying severity, impact, and frequency, the relationship between ocular surface sensitivity and ocular surface discomfort experienced during contact lens wear is unclear. The purpose of this review is to examine and summarize the current evidence for the impact of both historical and contemporary contact lens wear on ocular surface sensitivity, the etiology of changes in ocular surface sensitivity, contact lens wear-related factors associated with changes in ocular surface sensitivity, and the relationship between sensitivity and discomfort. Despite minimal effects on mechanical corneal sensitivity with contemporary soft contact lens wear, orthokeratology reduces corneal sensitivity through pressure-related effects. This review addresses the relevance of conjunctival and potentially lid margin sensitivity in tolerance and discomfort with contemporary lens wear and the impact of instrument and stimulus characteristics. Less invasive techniques particularly for lid margin sensitivity measurements are required. Given the potential interactions between a contact lens and the varied types of ocular surface nociceptors, instruments that allow for exploration of cold and chemical sensitivity particularly may better allow the effects of lens wear to be elucidated compared with those that explore high-threshold mechanical sensitivity alone. A better understanding of the relationships between lens wear and ocular surface sensitivity may result in improved management of contact lens discomfort.

Surgical Factors Affecting Changes in Ocular Surface Dynamics in the Early Postoperative Period After 25-Gauge Vitrectomy.

OBJECTIVES: Because vitrectomy-associated postoperative ocular surface changes are not well known, we evaluated such changes before and after vitrectomy in eyes with posterior segment diseases and investigated their associations with patients' characteristics and surgical procedures. METHODS: Thirty-five eyes of 32 consecutive patients (16 women; average age 66.6±11.1 years) were included in this prospective, noncomparative case series from tertiary care university hospital. Contact lens wearers and patients with history of ocular surgery or regular use of topical eyedrops were excluded. Patients had undergone primary 25-gauge vitrectomy at Osaka University Hospital in Japan between July and December 2016. Tear break-up time (TBUT), corneal and conjunctival fluorescein staining score (FSS), and tear meniscus height (TMH) were evaluated before, 1 week after, and 1 month after vitrectomy. RESULTS: Conjunctival FSS and TMH were significantly higher at 1 week after vitrectomy than preoperatively. However, they decreased significantly 1 month after. Changes in TBUT and corneal FSS showed a similar course at 1 week, but this was not statistically significant. Multiple linear regression analysis showed no significant correlation between significantly increased ocular parameters and patients' characteristics. By contrast, surgical time and combined cataract surgery significantly contributed to increased and decreased conjunctival FSS, respectively (P=0.011 and 0.033, respectively). Sclerotomy site suturing significantly contributed to increased TMH (P=0.025). CONCLUSIONS: We showed associations between ocular surface changes and specific surgical procedures. Caution should be exercised to minimize the effect of surgical procedures on the ocular surface during vitrectomy.

Nuclear parameters and chromatin remodeling in epithelial cells and lymphocytes from the palpebral conjunctiva of dogs with keratoconjunctivitis sicca.

OBJECTIVE: To study parameters related to nuclear morphology and chromatin remodeling in epithelial cells and lymphocytes from the inferior palpebral conjunctiva of dogs with and without keratoconjunctivitis sicca (KCS). ANIMALS STUDIED: Thirty-two dogs (64 eyes) were included in the study. Based on the tear production measured by Schirmer tear test 1, the dogs were distributed into control and KCS groups. PROCEDURES: Epithelial cells and lymphocytes were collected by conjunctival brush cytology, fixed on glass slides, and subjected to the Feulgen reaction, a topochemical method specific for DNA/chromatin. Feulgen-stained cells were studied by microscopy and video image analysis to establish nuclear size (area and perimeter) and shape (relative nuclear roundness factor = RNRF), DNA content (ploidy), and compaction and texture of chromatin. RESULTS: Conjunctival samples in the KCS group showed infiltration of inflammatory and immune cells. Micronuclei, snake-like chromatin, aberrant chromosomes, and goblet cells were not detected. Compared with the controls, cells on the conjunctival surface of dogs with KCS showed altered nuclei. Conjunctival epithelial cells were more affected by KCS (changes in nuclear size, shape, DNA content, and chromatin compaction) than lymphocytes (changes in chromatin compaction, only). Significant chromatin decompaction was observed in both conjunctival epithelial cells and lymphocytes. CONCLUSIONS: Our results show that KCS promotes chromatin remodeling in epithelial cells and lymphocytes on the conjunctival surface of dogs. The changes described in this study are different from those reported for conjunctival cell nuclei of human KCS patients.

Ant Bites Conjunctival Tissue: The ABCs of Removing an Ocular Ant Foreign Body.

BACKGROUND: A variety of insect-related ocular injuries have been reported in the literature. However, no reports have been published documenting injuries resulting from exposure of the ocular surface to ants. This is surprising, given the relatively ubiquitous presence of ants. This is the first known case report to describe various techniques utilized in the removal of ants from the ocular surface. CASE REPORT: This case report details the presentation of a distressed 24-year-old woman who presented to the Emergency Department with an ocular foreign body associated with pain and increased lacrimation. She was identified to have an ant adherent to her conjunctiva. Various techniques of removal were performed, with the ant finally removed without any trauma to underlying tissues. CONCLUSION: This is the first case report to detail various techniques utilized in the removal of ants from the ocular surface, and discusses salient features that treating physicians should be aware of in managing patients presenting with ant bites.

EFFECT OF SUN EXPOSURE DURATION ON CYCLOOXYGENASE-2 EXPRESSION IN THE CONJUNCTIVA.

Pterygium is a multifactorial proliferative pathologic change of bulbar conjunctiva. The purpose of this study was to determine the effect of the duration of exposure to solar radiation (expressed in years) on the incidence of positive cyclooxygenase-2 (COX-2) finding in conjunctival tissue in two groups of patients. Group 1 consisted of 68 patients with primary pterygium having undergone conjunctival autograft transplantation. Group 2 consisted of 43 patients with morphologically unchanged conjunctivae that were harvested during cataract surgery. All 111 specimens were submitted to immunohistochemical staining for monoclonal COX-2 antibody (1:100; M361701 MO A-HU, Dako, Santa Clara, California, USA). The immunostaining intensity in the surface epithelium was scored using the following grading system: 0 no immunostaining; + weak immunostaining (few cells being positive focally or scattered); ++ medium immunostaining; and +++ strong immunostaining (diffuse staining throughout the tissue). The analysis of COX-2 activity yielded 29 (42.6%) positive findings in group 1 and 27 (62.8%) positive findings in group 2. Group 2 consisted of statistically significantly older individuals with a history of considerably longer sun exposure. Statistical analysis proved the duration of exposure to solar radiation to be the most important factor in positive COX-2 findings.

Vegetating erosive cutaneous lesions and pyogenic granuloma in the course of mucous membrane pemphigoid: a case report and review of literature.

Mucous membrane pemphigoid (MMP) is a group of chronic autoimmune sub-epithelial blistering disorders, which mostly affect the oral mucosa and the conjunctiva. MMP is very diverse in terms of both the clinical and immunological features (IgG and IgA autoantibodies may react with different antigens). MMP can be induced by infections and medication, including ophthalmologic medication, which may lead to the development of eye lesions. In contrast, a vegetating variant of MMP is extremely rare. Here, we report an MMP case that demonstrated unusual clinical features, that is, pyogenic granulomas on the conjunctivae and extensive vegetating erosions on the skin of intertriginous regions. All these lesions were considered to be induced by unconventional medication containing arsenic.

[Analysis of corneal and conjunctival sensitivities and its related factors of premature babies].

Objective: To analyse the corneal and conjunctival sensitivities of premature babies and to study the relevant influencing factors. Methods: Cross-sectional study. One hundred premature infants born at Women's Hospital School of Medicine Zhejiang University between May 2015 and September 2015 were enrolled, among which 51 were male (51%) and 49 were female (49%), the mean gestational age was (30.93±1.75)w, the mean corrected gestational age was (33.65±1.53)w, the mean birth weight was (1 592±336)g. The thresholds of cornea and conjunctiva of infants' left or right eyes were measured with Cochet-Bonnet aesthesiometer at 8-10 o'clock every morning when they naturally woke up, the minimum length of nylon wire that induced three successive times of eye-blink responses was recorded. Paired sample t test was used to compare the corneal and conjunctival sensitivities, the ocular surface sensitivities of preterm infants of different gender were compared using independent samples t-test, Pearson correlation and multiple linear regression analysis was conducted to analyze the correlation of corneal and conjuncitval sensitivities with gestational age, birth weight, age and corrected gestational age. Results: The mean corneal sensitivity was (44.85±5.53) mm and the mean conjunctival sensitivity was (23.50±5.48)mm in premature babies, corneal sensitivity was significantly higher than conjunctival sensitivity (t=25.620, P<0.001). No statistical significance was found between male and female preterm infants in corneal sensitivity [(44.80±5.83) mm vs. (44.90±5.25) mm, t=-0.085, P=0.933] and conjunctival sensitivity[(23.14±5.83) mm vs. (23.88±5.13) mm, t=-0.673, P=0.502]. Pearson correlation analysis showed that corneal sensitivity was significantly associated with conjunctival sensitivity in prematurity(r=0.676, P<0.001). There was significant correlation between corneal sensitivity and age, corrected gestational age (r=0.238, P=0.017; r=0.679, P<0.001), however no significant correlation was found between corneal sensitivity and gestational age, birth weight in preterm infants (r=0.067, P=0.510; r=-0.179, P=0.075). There was significant correlation between conjunctival sensitivity and corrected gestational age (r=0.490, P<0.001), however no significant correlation was found between conjunctival sensitivity and gestational age, birth weight and age in preterm infants (r=0.078, P=0.439; r=-0.096, P=0.344; r=0.151, P=0.133). Multiple linear regression revealed that corneal sensitivity(Y1) was positively correlated with corrected gestational age(X), the regression equation was Y1=2.45X-37.52, the conjunctical sensitivity(Y2) was also positively correlated with corrected gestational age(X), the regression equation was Y2=1.75X-35.41. Conclusions: The corneal sensitivity is higher than conjunctival sensitivity in premature babies.No statistical significance is found between male and female preterm infants in corneal sensitivity and conjunctival sensitivity. The corneal sensitivity and conjunctival sensitivity are correlated with corrected gestational age in preterm infants. The corneal and conjunctival sensitivities of premature babies tend to increase along with the increase of corrected gestational age. (Chin J Ophthalmol, 2018, 54: 115-119).

Effects of Muller's muscle-conjunctival resection for ptosis on ocular surface scores and dry eye symptoms.

This article evaluates the effects of Muller's muscle-conjunctival resection (MMCR) on ocular surface scores and dry eye symptoms. Forty-six patients were enrolled in the study. Eighteen underwent bilateral upper eyelid skin excision with MMCR and 28 underwent bilateral upper eyelid skin-only excision (control group). The Salisbury Eye Evaluation Questionnaire and an ocular surface evaluation protocol consisting of Schirmer's test, tear break-up time (TBUT), fluorescein and rose bengal corneal staining were performed during the pre-operative consultation and on postoperative days 7, 30, and 90. Improvement in symptoms questionnaire scores from baseline was observed on postoperative day 90 in the blepharoplasty plus MMCR group. There was no change in questionnaire scores in patients who underwent blepharoplasty alone. No between-group difference in Schirmer's test, TBUT, or fluorescein and rose bengal staining was found at any time point. In the blepharoplasty-only (control group), the fluorescein staining score was reduced on postoperative day 30 as compared to baseline, but not on day 90. In this sample, addition of MMCR to upper eyelid blepharoplasty did not worsen ocular surface scores or dry eye symptoms.

Outcomes of levator advancement and Müller muscle-conjunctiva resection for the repair of upper eyelid ptosis.

Both the Müller muscle-conjunctiva resection (MMCR) and levator advancement (LA) procedures can be used to manage ptosis in patients with good levator function. The aim of this article is to evaluate the efficacy and cosmetic outcomes of the two procedures. The clinical records of 29 consecutive eyelids of 26 patients undergoing MMCR and 30 eyelids of 23 patients undergoing LA were analysed. Eleven (42%) in the LA group and 9 (39%) in the MMCR group were male. The preoperative eyelid measurements were significantly different in the LA compared to the MMCR groups, in terms of palpebral aperture (PA) (6.3 vs 7.4, p = 0.01), marginal reflex distance 1 (MRD1) (-0.1 vs 1.5, p < 0.001) and levator function (LF) (12.1 vs 13.4, p = 0.03). The MRD1 1 month post-surgery was slightly less in the LA group compared to the MMCR group (2.6 vs 3.18 mm, p = 0.047) but not significantly different at months 3 and 6. The final change in MRD1 was significantly higher in the LA group (2.93 vs 1.76, p = 0.004). The MMCR group had a lower incidence of lid contour abnormalities (0% vs 20%, p = 0.01) and overcorrection (0% vs 13%, p = 0.04). There was no statistically significant difference in the rates of undercorrection in either group. Both the MMCR as well as LA procedures are effective for mild to moderate ptosis in patients with good levator function. Patients undergoing MMCR had higher success rates, better preservation of the natural lid contour, and a lower incidence of overcorrection than patients undergoing LA.

Microcirculatory Bed, Microcirculation, and Smoking-Associated Endothelial Dysfunction in Young Adults.

Computer-assisted video biomicroscopy of bulbar conjunctiva was employed to examine the sequelae of endothelial dysfunction manifested by microcirculatory bed abnormalities and microcirculation disturbances. The signs of endothelial dysfunction provoked by tobacco smoking in young adults disappeared after cessation of smoking, which resulted in pronounced widening of arterioles and capillaries as well as moderation of intravascular erythrocyte aggregation.

Impact of Eye Cosmetics on the Eye, Adnexa, and Ocular Surface.

Despite the fact that cosmetic products undergo rigorous testing to ensure they are safe for human use, some users report mild discomfort following their application. The cutaneous changes, such as allergic dermatitis, are well reported, but the ocular changes associated with eye cosmetic use are less so. Some pigmented cosmetic products may accumulate within the lacrimal system and conjunctivae over many years of use, but immediate reports of eye discomfort after application are most common. Changes to the tear film and its stability may occur shortly after application, and contact lens wearers can also be affected by lens spoliation from cosmetic products. Additionally, creams used in the prevention of skin aging are often applied around the eyes, and retinoids present in these formulations can have negative effects on meibomian gland function and may be a contributing factor to dry eye disease. The aim of this review is to summarize current knowledge regarding the impact of cosmetic products on the eye, ocular surface, and tear film.

Hypoxia as pathogenic factor affecting the eye tissues: The selective apoptotic damage of the conjunctiva and anterior epithelium of the cornea.

The effect of acute hypoxia on the occurrence of apoptosis in eye cells in rats placed in a pressure chamber was studied. Selective primary lesion of cells of the conjunctiva and the anterior corneal epithelium was found. A possible role of the simulated hypoxic conditions in the dry eye syndrome pathogenesis, which is accompanied by primary lesion of cells in the anterior eye surface tissues is discussed.

Bilirubin Concentrations in Jaundiced Neonates with Conjunctival Icterus.

OBJECTIVES: To assess the total serum bilirubin (TSB) levels at which conjunctival icterus is observed in neonates of ≥34 weeks gestation during the first week of life. STUDY DESIGN: Two convenience samples of neonates were examined for conjunctival icterus within 4 hours of TSB measurements. A concurrent assessment of cephalopedal cutaneous icterus was performed and the TSB characterized using the Bhutani hour-specific risk zone nomogram. RESULTS: Two hundred forty neonates were studied of which 76 had conjunctival icterus. Conjunctival icterus was always accompanied by cutaneous jaundice to at least the chest and more often than not a TSB >14.9 mg/dL (255 umol/L) consistently in the 76th%-95th% to >95th% range on the Bhutani nomogram. Only a few infants with TSB in the range of 10-14.9 mg/dL (171-255 umol/L) had conjunctival icterus. CONCLUSIONS: Conjunctival icterus was observed in a subset of jaundiced neonates and associated with elevated hour-specific TSB levels frequently >95th% on the Bhutani nomogram. Conjunctival icterus is a sign of clinically relevant hyperbilirubinemia that merits a TSB measurement and evaluation of the infant.

Changes in Conjunctival Hemodynamics Predict Albuminuria in Sickle Cell Nephropathy.

BACKGROUND: Albuminuria is an early manifestation of deterioration in renal function in subjects with sickle cell disease (SCD). Hyperfiltration may be an early mechanism for kidney damage in SCD. The purpose of the current study was to determine the association between conjunctival hemodynamics and albuminuria in SCD subjects with preserved glomerular filtration rate. METHODS: Conjunctival microcirculation imaging was performed to measure conjunctival diameter and axial blood velocity (V) in 35 SCD and 10 healthy control subjects. Albuminuria, defined as albumin excretion ratio (AER), was obtained from the medical charts. Based on the 95% CI of conjunctival V in control subjects (0.40-0.60 mm/s), SCD subjects were allocated to 3 groups: V1 <0.40 mm/s (n = 7), V2 of 0.40-0.60 mm/s (n = 18) and V3 ≥0.60 mm/s (n = 10). RESULTS: Mean log(AER) measurements in the V1, V2 and V3 groups were 1.08 ± 0.67, 1.39 ± 0.59 and 2.00 ± 0.91 mg/g creatinine, respectively, and followed a positive linear trend from the V1 to V3 groups (p = 0.01). By multivariate linear regression analysis, conjunctival V significantly correlated with albuminuria (p = 0.01) independent of age, blood pressure, α-thalassemia, hematocrit, white blood cell count and lactate dehydrogenase concentration. CONCLUSIONS: Increased conjunctival V is associated with albuminuria in SCD subjects. Assessment of conjunctival microvascular hemodynamics may improve our understanding of the pathophysiology and clinical management of sickle cell nephropathy.

The conjunctival sensitivity in soft contact lens wearers.

We determined the influence of soft contact lenses (SCLs) on conjunctival sensitivity. A total of 26 volunteers (11 males, 15 females; mean age 28.3 ± 4.6 years; range 22-39 years) without dry eye were enrolled in the study. Subjects with a low corneal touch threshold, atopic keratoconjunctivitis, or vernal keratoconjunctivitis were excluded. In 26 participants, 12 were disposable SCL wearers. Touch thresholds were determined using a Cochet-Bonnet esthesiometer with a 0-60 mm nylon monofilament in 5 mm increments. The length (mm) was converted to tension (g/mm(2)). Mean touch sense thresholds in the SCL wearers (n = 12) and non-wearers (n = 14) were 10.7 ± 2.57 and 24.6 ± 7.3 g/mm(2) in the whole conjunctiva, and 9.07 ± 3.02 and 19.2 ± 7.8 g/mm(2) in the upper palpebral conjunctiva, respectively. Significant differences were observed in all locations (p < 0.01). The enhanced conjunctival sensitivity associated with SCL use may contribute to the dry eye-like symptoms in SCL users who do not have dry eye.

[Ocular surface acidity and buffering system (by studying the conjunctival sac)].

UNLABELLED: As any mucous membrane the conjunctiva is characterized by a definite pH value which guarantees-physiological functioning of the ocular surface. The most commonly used method of assessment is potentiometric pH measurement with ion-specific glass microelectrodes. The results, however, can be affected by such factors, as conjunctival sac zoning, tissue acidity, epithelial trauma, and reflex tear secretion. Few data and hypotheses are available on mechanisms of maintaining the acid-base balance of the conjunctival sac (bicarbonate buffering system in particular). OBJECTIVE: to study spatial variability of conjunctival tear fluid pH and possible mechanisms of its maintenance using original methods of acidity measurement and mineral content assessment. MATERIAL AND METHODS: Tear pH was determined in 42 healthy participants (84 eyes) by means of litmus test strips and computer- aided colorimetry. Electron probe microanalysis in combination with energy dispersive spectrometry was performed in 8 healthy participants (8 eyes, 8 samples). RESULTS: In the group of 42 healthy participants (84 eyes) the pH value of conjunctival tear fluid varied from 6.30 to 7.23 with the average of 6.76 and pH mode 6.74. The pH value of conjunctival mucous discharge was measured in 25 healthy participants (28 eyes) and varied from 7.00 to 8.00 with the average of 7.26 and pH mode 7.30. The main mineral components of tear fluid are chlorine, sodium, potassium, and boron. Borate buffer is regarded as a mechanism of maintaining the acid-base balance of the ocular surface. CONCLUSIONS: The developed method of pH measurement ensuresreliable determination of conjunctival sac acidity in accordance with zoning and heterogeneity of its media as well as the complex structure of the tear film. In a healthy population, the acidity of tear significantly differs from that of conjunctival mucous discharge. Soluble chlorine, sodium, potassium, and boron compounds are the prevailing mineral components of tear fluid. Borate buffer appears to be the most stable of all mechanisms of maintaining the acid-base status of tear fluid.

Association between dryness sensation and ocular surface temperature and conjunctival blood flow in soft contact lens wearers.

PURPOSE: To investigate the association between dryness, ocular surface temperature (OST), and conjunctival blood flow (CBF) in soft contact lens (SCL) wearers after airflow stimulation. METHODS: After recruiting 21 SCL wearers (mean age, 25.3 ± 4.2 years), subjects used two different daily disposable silicone hydrogel SCLs (narafilcon A and delefilcon A lenses). On three of four measurement days, excluding the first, OST, CBF, tear meniscus height (TMH), and non-invasive tear break-up time (NIBUT) were measured after airflow stimulation at a rate of 3 m/s for 10 min. The measurements were conducted without SCLs on the first and second days, and with different SCLs on the third and fourth days. Dryness was evaluated using the visual analogue scale (VAS). These parameters were compared between the two types of SCLs, and their association with the dryness sensation was then investigated. RESULTS: Dryness was significantly weakly correlated with OST (r = -0.375, p < 0.05) and CBF (r = 0.339, p < 0.05). TMH, NIBUT, and VAS scores for dryness with the delefilcon A lens (0.15 ± 0.05 mm, 3.7 ± 01.7 s and 29.4 ± 16.9) were significantly higher, longer, and lower, respectively, than those with the narafilcon A lens (0.12 ± 0.05 mm, 2.3 ± 1.7 s and 35.9 ± 17.0; p < 0.05, p < 0.01 and p < 0.01). The changes in the OST and CBF between with and without the delefilcon A lens (-0.36 ± 0.35 °C and 0.99 ± 0.19) were significantly small compared to the narafilcon A lens (-0.60 ± 0.42 °C and 1.11 ± 0.21; p < 0.01 for both comparisons). CONCLUSION: Dryness was correlated with OST and CBF, which indicates that when dryness was high, OST was low and CBF was high. These results suggest that OST and CBF assessments are effective for evaluating dryness sensation.

Human bulbar conjunctival hemodynamics in hemoglobin SS and SC disease.

The known biophysical variations of hemoglobin (Hb) S and Hb C may result in hemodynamic differences between subjects with SS and SC disease. The purpose of this study was to measure and compare conjunctival hemodynamics between subjects with Hb SS and SC hemoglobinopathies. Image sequences of the conjunctival microcirculation were acquired in 9 healthy control subjects (Hb AA), 24 subjects with SC disease, and 18 subjects with SS disease, using a prototype imaging system. Diameter (D) and blood velocity (V) measurements were obtained in multiple venules of each subject. Data were categorized according to venule caliber by averaging V and D for venules with diameters less than (vessel size 1) or greater than (vessel size 2) 15 µm. V in vessel size 2 was significantly greater than V in vessel size 1 in the AA and SS groups (P ≥ 0.009), but not in the SC group (P = 0.1). V was significantly lower in the SC group as compared to the SS group (P = 0.03). In AA and SS groups, V correlated with D (P ≤ 0.005), but the correlation was not statistically significant in the SC group (P = 0.08). V was inversely correlated with hematocrit in the SS group for large vessels (P = 0.03); however, no significant correlation was found in the SC group (P ≥ 0.2). Quantitative assessment of conjunctival microvascular hemodynamics in SS and SC disease may advance understanding of sickle cell disease pathophysiology and thereby improve therapeutic interventions.