Recommendations for eye care during the alarm state by the coronavirus disease pandemic COVID-19. / Recomendaciones para la atención oftalmológica durante el estado de alarma por la pandemia de enfermedad por coronavirus COVID-19.

OBJECTIVE: Minimize exposure to the SARS-CoV-2, reduce the chances of cross-transmission between patients and healthcare personnel, and prevent the development of postoperative complications from the management of patients with eye diseases during the 2019 coronavirus disease pandemic (COVID-19). METHODS: COVID-19 literature review and consensus establishment between different Spanish ophthalmology societies in order to provide guidelines and recommendations of maximum resources primarily conditioned by the state of alert, confinement and social distancing that occurs in Spain since March 16, 2020. RESULTS: The recommendations will promote the adoption of action and protection measures for eye care in outpatient clinics, surgical areas and hospitalization, for unconfirmed (asymptomatic and symptomatic) and confirmed COVID-19 patients. Measures must be adapted to the circumstances and availability of personal protective equipment in each of the centers and Autonomous Communities, which will be updated according to the pandemic phases and the measures adopted by the Spanish Government. CONCLUSIONS: During the COVID-19 pandemic, attention to the potential health risks to the population caused by coronavirus should prevail over the possible progression of the common eye diseases. Ophthalmologists and other eye care professionals must assume a possible progression of these diseases due to the impossibility of adequate patient follow-up.

Dynamic in vitro dehydration patterns of unworn and worn silicone hydrogel contact lenses.

PURPOSE: To evaluate the effect of wear on dynamic in vitro dehydration of silicone hydrogel (Si-Hi) contact lens (CL) using a previously described gravimetric procedure. METHODS: Five different silicone hydrogel (Si-Hi) contact lenses (CL) were evaluated after being worn by patients under daily wear conditions for 15 days to 1 month. Lenses were conditioned and disinfected with a multipurpose solution after each day of wear. Lenses were left to dehydrate in an analytical balance under controlled conditions of temperature and relative humidity and the results compared with data from new lens samples of the same power and material. Several quantitative parameters were obtained and compared between worn and unworn samples. RESULTS: The quantitative parameters derived from the dehydration curves showed statistically significant differences between worn and unworn lenses regarding the initial dehydration rate and ability to maintain their original hydration. Worn lenses showed shorter phase I duration (decreased by 30 to 60% compared to unworn samples), a significantly faster initial dehydration rate (increased by about 1%/minute), and lower water retention index (decreased by 10 to 20%) as derived from the initial cumulative dehydration. All the differences were statistically significant for all lenses (p < 0.05). CONCLUSION: The initial dehydration rates were significantly increased in all CL after wear. This could be of clinical interest because it represents the average initial dehydration rates during the first moments when the lens is left to dehydrate after a blink. This study suggests that even after the lenses had been equilibrated in saline solution for several days, the materials lose their ability to retain water.

Surface AFM microscopy of unworn and worn samples of silicone hydrogel contact lenses.

PURPOSE: To evaluate the qualitative and quantitative topographic changes in the surface of worn contact lenses (CLs) of different materials using atomic force microscopy (AFM). METHODS: The topography of five different CL materials was evaluated with AFM over a surface of 25 microm(2) according to previously published experimental setup. Average roughness (R(a)) and root mean square (Rms) values were obtained for unworn and worn samples. RESULTS: The R(a) value increased for balafilcon A (11.62-13.68 nm for unworn and worn samples, respectively), lotrafilcon A (3.67-15.01 nm for unworn and worn samples, respectively), lotrafilcon B (4.08-8.42 nm for unworn and worn samples, respectively), galyfilcon A (2.81-14.6 nm for unworn and worn samples, respectively), and comfilcon A (2.87-4.63 nm for unworn and worn samples, respectively). Differences were statistically significant for all lenses except Rms and R(a) for comfilcon A, and R(a) parameter for balafilcon A (p > 0.05). The least relative increase was observed for some balafilcon A samples and for some of these samples the roughness decreased after the lenses had been worn. CONCLUSION: The changes in surface roughness between unworn and worn lenses are different for different silicone-hydrogel materials. Overall all CLs increased the degree of surface roughness after being worn, even for very short periods of time. However, for samples of balafilcon A, roughness increases at a lower extent or even can decrease as compared to unworn samples of the same material due to filling of the macropores.

Biological oxygen apparent transmissibility of hydrogel contact lenses with and without organosilicon moieties.

The instrument oxygen transmissibility (IOT) of organosilicon hydrogels, measured by electrochemical procedures, is 5-10 times larger than that of conventional hydrogels. A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations by combining the IOT of the hydrogels and corneal parameters such as corneal thickness, corneal permeability and oxygen flux across the cornea. From these results the biological oxygen apparent transmissibility (BOAT) is obtained, an important parameter which an multiplication with the pressure of oxygen on the external part of the lens gives the oxygen flux onto the cornea. Contact lenses with oxygen transmissibility higher than 100 Dk/t units [1 Dk/t unit=10(-9) [cm(3) O(2) (STp) cm(-2)s(-1)(mmHg)(-1)] posses a large oxygen tension at the lens-cornea interface that substantially reduces the oxygen flux onto the cornea. Lenses whose oxygen transmissibility is lower than 50 Dk/t units allow a rather small oxygen flux onto the cornea under closed eyelids condition that prevent their use for extended wear.

Oxygen permeability of hydrogel contact lenses with organosilicon moieties.

Oxygen transport through two extended wear (day and night) hydrogel contact lenses that contain organosilicon moieties (balafilcon A and lotrafilcon A) was studied in the hydrate (hydrogel) and dry (xerogel) states. The water uptake increased the oxygen permeability [(Dk)app] and transmissibility [Dk/L(av)] coefficients of the dry materials by about 70%. The (Dk)app for the hydrated lenses was determined following the so-called stack procedure. The values obtained were 107 +/- 4 barrer for balafilcon A and 141 +/- 5 barrer for lotrafilcon A, about 5-10 times larger than those previously reported for conventional (without organosilicon moieties) extended wear hydrogels contact lenses. The Dk/L(av) for -3.00 diopter lenses (harmonic average thickness, L(av) = 75 +/- 2 microm for lotrafilcon, and 85 +/- 2 microm for balafilcon) was 123 +/- 6 barrer/cm for balafilcon A and 183 +/- 8 barrer/cm for lotralicon A. The minimum oxygen transmissibility 87 barrer/cm stipulated by Holden and Mertz to avoid corneal edema with extended wear contact can be easily achieved with lotrafilcon and balafilcon lenses of diverse dioptric powers if the central and peripheral thickness of the lenses are kept below the critical level of oxygen transmissibility.

Ocular physiology and artificial tears.

BACKGROUND: In this study, we evaluated the pH value of nine artificial tears solutions in order to investigate whether their pH changed over time. These solutions are designed to have a pH value within the ocular comfort range and to come close to the physiological tears' pH. METHODS: Fifteen bottles of each solution were randomly chosen from different production lots. Increments of 0.05 ml were taken daily from each bottle and measured daily, using a micropH 2002 Crison pH-meter over a period of 60 days. RESULTS: The values obtained fall within the ocular comfort range. Also, we obtained nonstatistically significant variations over time for each solution (p > 0.01). The results revealed differences between solutions, some solutions coming close to the tear's pH and others being slightly more acidic or alkaline. CONCLUSIONS: We may assume that all the solutions evaluated will not affect either the ocular physiology or the contact lens wear. The practitioners should know the properties of the solutions, thus selecting the adequate solution for each type of patient.

pH of multipurpose contact lens solutions over time.

The pH of nine different brands of multipurpose contact lens solutions available in Spain was determined over a period of 32 days after opening the bottles. Five bottles of nine solutions were used, each of which was buffered and obtained from different manufacturers. The pH measurements were taken using a micropH 2002 Crison pH-meter (accuracy +/- 0.001 pH units). Each solution was measured three times daily over the test period using 10-ml samples taken from the same container. Fluctuations in pH over time were observed but these were within the range of ocular comfort. The average pH of all the solutions tested proved to be between 6.99 and 7.56.

Comparative study of pH for different saline and multi-purpose contact lens solutions.

In this study, we determined the pH of different saline and multipurpose contact lens solutions available on the Spanish market. We examined 10 samples of 14 solutions, seven of which are saline solutions and seven multipurpose ones, from different manufacturers. Both types of solution were found to have significant variations in pH, with values ranging from 6.70 to 7.57 for the saline solutions and 6.84 to 7.63 for the multipurpose solutions. We concluded that the solutions should not affect the ocular physiological performance because their pH values are within the buffering capacity of the eye.

[Utilization of the ophthalmology service at the outpatient clinic of the "El Españoleto" de Xátiva Health Service of Valencia]. / Uso del servicio de oftalmología del ambulatorio del Servicio Valenciano de Salud "El Españoleto" de Xátiva.

This is a descriptive paper on the use of the Ophthalmology Service which operates from to 10 in the morning in the Valencia Outpatient Service, "El Españoleto", of Xàtiva, Valencia. An average of 24.48 consultations are made daily, which average 4 minutos 54 seconds each. The general rate of consultations per individual health service card per month reaches a value of 0.024 consultations. 29.62% of the most frequently made diagnoses are for refraction, 26.54% unknown and 7.73% for presbytia.