The Effects of Sex, Oral Contraception, and Menstrual Cycle Phase on Intraocular Pressure, Central Corneal Thickness, and Foveal Thickness: A Descriptive Analysis.

The primary goal of this study was to investigate the effects of sex, oral contraceptive (OC) use, and menstrual cycle phase on common ocular parameters assessed during ophthalmic evaluations, namely intraocular pressure (IOP), central corneal thickness (CCT), and foveal thickness (FT), in young healthy adults. We measured IOP, CCT, and FT in 60 participants (16 men, 16 contraceptive users, and 28 cycling women) over two sessions that characterized the menstrual cycle phase in women. For men in our study, two sessions were separated by two weeks. For women, the two sessions were scheduled during the follicular and luteal phases of the menstrual cycle. There was a trend towards higher IOP in men, and the difference was significant for white, non-Hispanic subjects and for white subjects considered separately. There was also a trend for thicker corneas in women, but men had significantly thicker foveae. CCT and FT were not different between men and OC-users, hinting at a moderating hormonal effect of oral contraceptive use. We found that IOP, CCT, and FT were equivalent between the follicular and luteal phases, which may be owing to the timing of our sessions. However, our findings strongly suggest that clinicians should consider contraceptive use during routine ophthalmic evaluations, as it could inform glaucomatous risk in women.

Macular pigment optical density and visual quality of life

PURPOSE: There is robust evidence that higher macular pigment concentrations help reduce both veiling and discomfort glare in patients with or without ocular disease. We investigated whether there was also a relationship between macular pigment optical density (MPOD) and patient surveys about glare or ocular discomfort. METHODS: We measured MPOD psychophysically in 23 healthy subjects and administered the National Eye Institute Visual Functioning Questionnaire (VFQ-25). Responses for each survey question were sorted from low (no limitation) to high (very severe limitation). The median response for each question was determined, and independent t-tests were performed on the mean MPOD values for survey responses above and below the median. We also performed a non-parametric correlation analysis between MPOD and survey responses. RESULTS: While the median response was "no limitation" for most (22 of 25) survey questions, responses were slightly higher for two questions concerning ocular discomfort and one question related to driving at night. MPOD levels were significantly higher in subjects that reported no discomfort in or around their eyes than in those that reported mild discomfort. There was also a trend toward higher MPOD levels in subjects who reported that pain in or around their eyes never limited their activity as well as in subjects who reported no difficulty driving at night. CONCLUSION: These preliminary findings are consistent with the well-established discomfort and glare hypotheses for MPOD. The current findings on subjective ocular discomfort in the absence of glare deserve further study

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Macular pigment optical density and visual quality of life.

PURPOSE: There is robust evidence that higher macular pigment concentrations help reduce both veiling and discomfort glare in patients with or without ocular disease. We investigated whether there was also a relationship between macular pigment optical density (MPOD) and patient surveys about glare or ocular discomfort. METHODS: We measured MPOD psychophysically in 23 healthy subjects and administered the National Eye Institute Visual Functioning Questionnaire (VFQ-25). Responses for each survey question were sorted from low (no limitation) to high (very severe limitation). The median response for each question was determined, and independent t-tests were performed on the mean MPOD values for survey responses above and below the median. We also performed a non-parametric correlation analysis between MPOD and survey responses. RESULTS: While the median response was "no limitation" for most (22 of 25) survey questions, responses were slightly higher for two questions concerning ocular discomfort and one question related to driving at night. MPOD levels were significantly higher in subjects that reported no discomfort in or around their eyes than in those that reported mild discomfort. There was also a trend toward higher MPOD levels in subjects who reported that pain in or around their eyes never limited their activity as well as in subjects who reported no difficulty driving at night. CONCLUSION: These preliminary findings are consistent with the well-established discomfort and glare hypotheses for MPOD. The current findings on subjective ocular discomfort in the absence of glare deserve further study.

Effects of Oral Antihistamines on Tear Volume, Tear Stability, and Intraocular Pressure.

The goal of this study was to investigate the effects of two commonly used oral antihistamines-diphenhydramine and loratadine-on tear volume, tear breakup time, and intraocular pressure. Placebo, diphenhydramine, and loratadine were administered for one week to 33 subjects experimentally blind to the treatment given. All the subjects received all three treatments over a period of six weeks. The outcome measures were the change in phenol red thread test (PRT), the tear breakup time (TBUT), and the intraocular pressure (IOP) of both eyes evaluated by experimentally masked observers. Neither of the mean changes in TBUT or IOP depended on the treatment given, but there was a significant monocular decrease in tear volume from diphenhydramine use. While we used an adequate treatment washout period of seven days, our investigation was limited by the short treatment times and inclusion of only young healthy patients. Overall, however, these results suggest that systemic diphenhydramine use should be limited to increase the effectiveness of conventional therapies. Clinicians should have fewer reservations about recommending the use of loratadine concurrent with dry eye treatments.

Is the Helmholtz-Kohlrausch Effect More Robust in Women?

For gray or achromatic objects, brightness is a relatively simple transformation where very low luminance levels are perceived as black and higher levels are perceived as white. For chromatic objects, the transformation is more complex, depending on color purity as well. This influence of color purity on a color's perceived brightness is a well-established phenomenon known as the Helmholtz-Kohlrausch (H-K) effect. We investigated gender differences in the H-K effect by measuring brightness (via direct brightness matching [DBM]) and luminance (via heterochromatic flicker photometry [HFP]) at five wavelengths (450, 520, 560, 580, and 650 nm) perceived as blue, green, green-yellow, yellow, and red hues. We compared DBM/HFP ratios between 13 males and 18 females. Based on previous evidence of a female advantage in chromatic processes, we hypothesized that DBM/HFP ratios would be higher in female subjects. While HFP measures were essentially the same between male and female subjects, DBM measures and DBM/HFP ratios were significantly higher for female subjects than males. There were no significant effects of contraceptive use based on a post hoc comparison. We also derived simple models of brightness as a function of luminance and saturation, which further suggest gender dimorphism in the H-K effect.

The Dominant Eye: Dominant for Parvo- But Not for Magno-Biased Stimuli?

Eye dominance is often defined as a preference for the visual input of one eye to the other. Implicit in this definition is the dominant eye has better visual function. Several studies have investigated the effect of visual direction or defocus on ocular dominance, but there is less evidence connecting ocular dominance and monocular visual thresholds. We used the classic "hole in card" method to determine the dominant eye for 28 adult observers (11 males and 17 females). We then compared contrast thresholds between the dominant and non-dominant eyes using grating stimuli biased to be processed more strongly either by the magnocellular (MC) or parvocellular (PC) pathway. Using non-parametric mean rank tests, the dominant eye was more sensitive overall than the non-dominant eye to both stimuli (z = -2.54, p = 0.01). The dominant eye was also more sensitive to the PC-biased stimulus (z = -2.22, p = 0.03) but not the MC-biased stimulus (z = -1.16, p = 0.25). We discuss the clinical relevance of these results as well as the implications for parallel visual pathways.

An atypical presentation of visual conversion disorder / Presentación atípica del trastorno de conversión visual

Nonorganic vision loss accounts for up to 5% of patients and presents in two forms, malingering and visual conversion disorder (VCD). It is described a case of VCD in a new mother struggling both with her husband being deployed overseas and the recent death of her father. In addition, she had been evaluated for a concussion secondary to a motor vehicle accident three months prior. An inexpensive series of clinical tests were performed to rule out organic disease and obtained equivocal results. Some tests revealed intact vision in the affected eye while others supported a neurological cause for the vision loss. However, the patient quickly recovered normal visual acuity when encouraged to discuss situations that have been causing emotional stress. This almost immediate recovery of vision confirmed the diagnosis of VCD. This report should make primary eye care professionals more aware of visual conversion disorder and its clinical evaluation (AU)

La pérdida de la visión no orgánica afecta a cerca del 5% de los pacientes, y se presenta bajo dos formas: simulación y trastorno de conversión visual (VCD). Se describe un caso de VCD en una madre primípara que se esforzaba por superar cambios repentinos en su vida con su marido en el extranjero y la reciente muerte de su padre. Además, había sido examinada a causa de una conmoción secundaria a un accidente de tráfico hacía tres meses. Se le realizaron una serie de pruebas clínicas no asociadas a un alto coste para descartar la enfermedad orgánica, obteniendo resultados equívocos. Algunas pruebas mostraban una visión intacta en el ojo afectado, mientras otras respaldaban una causa neurológica para la pérdida de visión. Sin embargo, la paciente recuperó rápidamente la agudeza visual cuando le animé a comentar las situaciones que le habían originado el estrés emocional. Esta recuperación de la visión casi inmediata confirmó el diagnóstico de VCD. Este caso clínico debería servir de concienciación a los profesionales de la atención visual primaria en lo referente al trastorno de conversión visual y de su evaluación clínica (AU)

Macular Pigment and Visual Performance in Low-Light Conditions.

PURPOSE: By reducing rod intrusion and improving efficiency of neural signaling throughout the visual system, macular pigment (MP) could improve many aspects of visual performance in low-light level conditions. Our study examined this possibility for a variety of visual performance parameters, including spatial resolution, dark adaptation kinetics, and color detection. METHODS: Twenty-seven subjects participated in the study. Spatial profiles of MP optical density (MPOD) were determined by using heterochromatic flicker photometry. Mesopic- and scotopic-adaptation level experiments were conducted in Maxwellian view. RESULTS: Subjects with higher MPOD required significantly lower contrast to detect the mesopic-level resolution targets; this effect became stronger with increasing spatial frequency. Dark adaptation recovery times were significantly faster as a function of MPOD (by nearly 2 minutes for the lowest mesopic-level task [high versus low MPOD]; P < 0.001). Absolute scotopic thresholds were also significantly associated with MPOD (P < 0.001). Macular pigment optical density was inversely associated with detection of yellow (P < 0.001), and, paradoxically, approached a significant positive correlation with the detection of blue (P = 0.06). CONCLUSIONS: Macular pigment appears to enhance visual function in low-light conditions. Based on the results of this study, it can be said that MP extends the range of foveal vision into lower light. Additionally, MP appears to enhance dark adaptation kinetics, which suggests that increased MPOD leads to more efficient photopigment regeneration. The findings of the color detection portion of the study are suggestive of an active compensatory mechanism that offsets absorption by MP in order to maintain normal color perception.

An atypical presentation of visual conversion disorder.

Nonorganic vision loss accounts for up to 5% of patients and presents in two forms, malingering and visual conversion disorder (VCD). It is described a case of VCD in a new mother struggling both with her husband being deployed overseas and the recent death of her father. In addition, she had been evaluated for a concussion secondary to a motor vehicle accident three months prior. An inexpensive series of clinical tests were performed to rule out organic disease and obtained equivocal results. Some tests revealed intact vision in the affected eye while others supported a neurological cause for the vision loss. However, the patient quickly recovered normal visual acuity when encouraged to discuss situations that have been causing emotional stress. This almost immediate recovery of vision confirmed the diagnosis of VCD. This report should make primary eye care professionals more aware of visual conversion disorder and its clinical evaluation.

Depression and burnout symptoms among Air Force family medicine providers.

This study investigated the prevalence of depression and burnout symptoms among family medicine providers on active duty in the US Air Force. Results demonstrated that 84% of those surveyed scored positive for degrees of depression symptoms; only sex differences were significant.

Visual disruption using the thermal lensing effect in the human eye: pilot study.

At select wavelengths, near infrared (IR) light is absorbed in the preretinal media of the eye. This produces small transient increases in temperature that temporarily alter the local index of refraction. If the IR exposure is sufficiently high, a momentary reduction in the focusing power of the eye can be induced through an effect known as thermal lensing. Fundamental optical interaction and safety aspects of this phenomenon have been demonstrated previously in animal and artificial eye models. However, whether the effect will induce an observable visual change in human subjects has not been explored. Here, results of a pilot study are shown where eight human subjects were exposed to an IR laser at levels that were below the safe exposure limit. The exposures did induce a transient visual distortion if sufficiently high levels were used. While the description of the visual change varied between subjects, this experiment was able to determine a general guideline for power needed to induce significant effects in human subjects.

Macular pigment and visual performance in glare: benefits for photostress recovery, disability glare, and visual discomfort.

PURPOSE: One theory of macular pigment's (MP) presence in the fovea is to improve visual performance in glare. This study sought to determine the effect of MP level on three aspects of visual performance in glare: photostress recovery, disability glare, and visual discomfort. METHODS: Twenty-six subjects participated in the study. Spatial profiles of MP optical density were assessed with heterochromatic flicker photometry. Glare was delivered via high-bright-white LEDs. For the disability glare and photostress recovery portions of the experiment, the visual task consisted of correct identification of a 1° Gabor patch's orientation. Visual discomfort during the glare presentation was assessed with a visual discomfort rating scale. Pupil diameter was monitored with an infrared (IR) camera. RESULTS: MP level correlated significantly with all the outcome measures. Higher MP optical densities (MPODs) resulted in faster photostress recovery times (average P < 0.003), lower disability glare contrast thresholds (average P < 0.004), and lower visual discomfort (P = 0.002). Smaller pupil diameter during glare presentation significantly correlated with higher visual discomfort ratings (P = 0.037). CONCLUSIONS: MP correlates with three aspects of visual performance in glare. Unlike previous studies of MP and glare, the present study used free-viewing conditions, in which effects of iris pigmentation and pupil size could be accounted for. The effects described, therefore, can be extended more confidently to real-world, practical visual performance benefits. Greater iris constriction resulted (paradoxically) in greater visual discomfort. This finding may be attributable to the neurobiologic mechanism that mediates the pain elicited by light.