Genetic testing for inherited ocular conditions in a developing country.

Background: Inherited ocular conditions are a frequent cause of blindness. Gene therapy has encouraged the development of genetic testing, currently able to detect up to 80% of mutations in contrast to the 5% sensitivity achieved a few decades ago.Materials and methods: One hundred sixty-three patients with suspected genetic ocular disorders who were referred to a single clinician between August 2014 and August 2019 underwent a thorough ophthalmologic examination. Those diagnosed with congenital cataract, retinoblastoma, anterior segment dysgenesis, autoimmune retinal disease, posterior microphthalmia, or cobalamin C deficiency were excluded, along with patients who opted against genetic testing. Included probands were classified into a diagnostic clinical category and offered genetic testing. Blood samples were sent to foreign accredited diagnostic laboratories, followed by clinical interpretation of the results.Results: Of the 163 patients referred, 104 were enrolled in the study. Median age at disease onset was 2 years (range, 0 to 43 years). A molecular diagnosis was established at a median age of 10 years (range, 0.4 to 50 years). Disease-causing genotypes were identified in 82 of the probands, indicating a mutation detection rate of 78.8%. Mutations were identified in 38 genes, ABCA4 being the most commonly affected (23% of mutations), followed by CRB1 (13% of mutations). Whole-exome sequencing was performed in 6 patients, resulting in a definite diagnosis in 3 (50%).Conclusions: Molecular testing for inherited ocular conditions is feasible in developing countries by sending samples to certified foreign laboratories, with a mutation detection rate comparable to published values in developed countries. Further studies to identify more disease-causing genes may improve the overall sensitivity.

A national telemedicine network for retinopathy of prematurity screening.

PURPOSE: To report the results of retinopathy of prematurity (ROP) screening by a telemedicine system in Chile and evaluate its usefulness for referring patients who require treatment. METHODS: Premature infants at risk of developing ROP from 11 neonatal intensive care units were included. Screening was performed on all infants born at a gestational age of <32 weeks and/or birth weight of <1500 g. A trained nonphysician operator used an imaging system to capture retinal images, which were reviewed by two independent ROP experts. All infants that required treatment were referred for further evaluation. RESULTS: The study included 2,048 eyes of 1,024 premature infants. Mean gestational age was 28.8 ± 2.2 weeks, and mean birth weight was 1128 ± 279 g. A total of 5,263 telemedicine examinations were performed and reported. The average number of image sets per patient was 2.6 ± 2.5. Of the 5,263 images, 4,903 (93%) were recorded to at least the end of zone II; 5,172 (98%) were graded as having good quality, allowing for staging of ROP disease. Forty-two infants (4%) were referred for treatment. Discharged patients with ROP type 2 that regressed did not present with any complications or adverse effects during 6 months' follow-up. CONCLUSIONS: Our study demonstrates the utility of telemedicine screening for ROP with ophthalmologist readers in a developing country. Telemedicine screening was able to detect treatment-requiring ROP. Most of the images had good quality and showed the end of zone II, two variables sufficient to discharge patients.

Bilateral retinoblastoma with one eye manifesting only posterior chamber infiltration and no retinal involvement.

We report the case of a 23-month-old girl with bilateral retinoblastoma that demonstrated absence of retinal lesions in one eye but had an isolated white tumor in the posterior chamber. Genetic testing confirmed a novel and de novo RB1 germline mutation in the proband that was not carried by her parents. After intravenous chemotherapy and brachytherapy to the eye with apparently disease-free retina, anatomic and functional preservation of the eye was achieved. The patient has been in remission for 18 months.

Using cost-effective intra-arterial chemotherapy to treat retinoblastoma in Chile.

Intra-arterial chemotherapy (IAC) has proved to be an effective treatment for retinoblastoma, but can be very expensive in developing countries. We report 2 patients from Chile in whom IAC resulted in globe salvation. Both patients had their medical care provided by the public health system and had failed standard therapy.

Dynamics of tear fluid desiccation on a glass surface: a contribution to tear quality assessment.

BACKGROUND: Fern-like crystalloids form when a microvolume of tear is allowed to dry out at ambient conditions on a glass surface. Presence of crystalloids in tear "microdesiccates" is used to evaluate patients with Dry-Eye disease. This study aims to examine morphologically the desiccation process of normal tear fluid and to identify changes associated with accelerated tear evaporation. Tear microdesiccates from healthy (Non-Dry Eye) and Dry Eye subjects were produced at ambient conditions. Microdesiccate formation was monitored continuously by dark-field video microscopy. Additionally, accelerated desiccation of tear samples from healthy subjects was conducted under controlled experimental conditions. Particular morphological domains of tear microdesiccates and their progressive appearance during desiccation were compared. RESULTS: In normal tear microdesiccates, four distinctive morphological domains (zones I, II, III and transition band) were recognized. Stepwise formation of those domains is now described. Experimentally accelerated desiccation resulted in marked changes in some of those zones, particularly involving either disappearance or size reduction of fern-like crystalloids of zones II and III. Tear microdesiccates from Dry Eye subjects may also display those differences and be the expression of a more synchronous formation of microdesiccate domains. CONCLUSION: Morphological characteristics of tear microdesiccates can provide insights into the relative rate of tear evaporation.

Dynamics of tear fluid desiccation on a glass surface: a contribution to tear quality assessment

BACKGROUND: Fern-like crystalloids form when a microvolume of tear is allowed to dry out at ambient conditions on a glass surface. Presence of crystalloids in tear "microdesiccates" is used to evaluate patients with Dry-Eye disease. This study aims to examine morphologically the desiccation process of normal tear fluid and to identify changes associated with accelerated tear evaporation. Tear microdesiccates from healthy (Non-Dry Eye) and Dry Eye subjects were produced at ambient conditions. Microdesiccate formation was monitored continuously by dark-field video microscopy. Additionally, accelerated desiccation of tear samples from healthy subjects was conducted under controlled experimental conditions. Particular morphological domains of tear microdesiccates and their progressive appearance during desiccation were compared. RESULTS: In normal tear microdesiccates, four distinctive morphological domains (zones I, II, III and transition band) were recognized. Stepwise formation of those domains is now described. Experimentally accelerated desiccation resulted in marked changes in some of those zones, particularly involving either disappearance or size reduction of fern-like crystalloids of zones II and III. Tear microdesiccates from Dry Eye subjects may also display those differences and be the expression of a more synchronous formation of microdesiccate domains. CONCLUSION: Morphological characteristics of tear microdesiccates can provide insights into the relative rate of tear evaporation.

[Natural history of diabetic retinopathy in a retrospective cohort of type 1 diabetics]. / Historia natural de retinopatía diabética en un estudio a largo plazo en pacientes con diabetes tipo 1. Factores de riesgo para progresión a enfermedad proliferante.

BACKGROUND: Diabetic retinopathy is one of the most common causes of blindness among adults. AIM: To report the natural history of diabetic retinopathy among Chilean patients with type 1 diabetes followed for a mean of 18 years. MATERIAL AND METHODS: Retrospective review of medical records of 39 patients aged 26 to 70 years, (20 females, 78 eyes) with type 1 diabetes controlled by the same ophthalmologist from 1971 to 2008. A questionnaire was sent to each patient and their treating physician to request information about the evolution of the disease and metabolic control. RESULTS: The questionnaire was answered by 24 patients (62%) and 21 attending physicians (54%). Small hard drusen were observed in 25 patients (64%). In 12 cases the drusen were detected before the development of any type of retinopathy. Eleven women became pregnant and retinopathy progressed in four of them. Twenty three patients (59%) developed proliferative diabetic retinopathy (PDR). Patients with PDR had a significantly longer duration of diabetes and worse glycemic control. There was a higher frequency of diabetic nephropathy in the PDR group, but only 13 patients out of 23 with PDR had nephropathy. The retinopathy progressed to high risk PDR two years after successful kidney-pancreas transplantation in one patient. CONCLUSIONS: In patients with type 1 diabetes mellitus, small hard drusen may be the initial manifestation of diabetic retinopathy. Risk factors for progression to PDR were duration of diabetic and poor glycemic control. Nephropathy was more prevalent in patients with PDR, but a significant group of PDR patients did not have demonstrable nephropathy.

Historia natural de retinopatía diabética en un estudio a largo plazo en pacientes con diabetes tipo 1. Factores de riesgo para progresión a enfermedad proliferante / Natural history of diabetic retinopathy in a retrospective cohort of type 1 diabetics

Background: Diabetic retinopathy is one of the most common causes of blindness among adults. Aim: To report the natural history of diabetic retinopathy among Chilean patients with type 1 diabetes followed for a mean of 18 years. Material and methods: Retrospective review of medical records of 39 patients aged 26 to 70 years, (20 females, 78 eyes) with type 1 diabetes controlled by the same ophthalmologist from 1971 to 2008. A questionnaire was sent to each patient and their treating physician to request information about the evolution of the disease and metabolic control. Results: The questionnaire was answered by 24 patients (62 percent) and 21 attending physicians (54 percent). Small hard drusen were observed in 25 patients (64 percent). In 12 cases the drusen were detected before the development of any type of retinopathy. Eleven women became pregnant and retinopathy progressed in four of them. Twently three patients (59 percent) developed proliferative diabetic retinopathy (PDR). Patients with PDR had a significantly longer duration of diabetes and worse glycemic control. There was a higher frequency of diabetic nephropathy in the PDR group, but only 13 patients out of 23 with PDR had nephropathy. The retinopathy progressed to high risk PDR two years after successful kidney-pancreas transplantation in one patient. Conclusions. In patients with type 1 diabetes mellitus, small hard drusen may be the initial manifestation of diabetic retinopathy. Risk factors for progression to PDR were duration of diabetic and poor glycemic control. Nephropathy was more prevalent in patients with PDR, but a significant group of PDR patients did not have demonstrable nephropathy (RevMéd Chile 2009; 137:1145-52).

Encefalomielitis diseminada aguda en pediatría / Acute disseminated encephalomyelitis in children

La encefalomielitis diseminada aguda es una patología poco frecuente, pero de gran impacto en salud pública. Se sospecha clínicamente y diagnóstica en base a los hallazgos de estudios imagenológicos, como resonancia nuclear magnética. En este artículo se realiza una revisión de la literatura para orientar al pediatra en caso de sospecha del diagnóstico.