Climatic droplet keratopathy in the Argentine Patagonia

TFOS Lifestyle Report: Impact of environmental conditions on the ocular surface

Environmental risk factors that have an impact on the ocular surface were reviewed and associations with age and sex, race/ethnicity, geographical area, seasonality, prevalence and possible interactions between risk factors are reviewed. Environmental factors can be (a) climate-related: temperature, humidity, wind speed, altitude, dew point, ultraviolet light, and allergen or (b) outdoor and indoor pollution: gases, particulate matter, and other sources of airborne pollutants. Temperature affects ocular surface homeostasis directly and indirectly, precipitating ocular surface diseases and/or symptoms, including trachoma. Humidity is negatively associated with dry eye disease. There is little data on wind speed and dewpoint. High altitude and ultraviolet light exposure are associated with pterygium, ocular surface degenerations and neoplastic disease. Pollution is associated with dry eye disease and conjunctivitis. Primary Sjögren syndrome is associated with exposure to chemical solvents. Living within a potential zone of active volcanic eruption is associated with eye irritation. Indoor pollution, "sick" building or house can also be associated with eye irritation. Most ocular surface conditions are multifactorial, and several environmental factors may contribute to specific diseases. A systematic review was conducted to answer the following research question: "What are the associations between outdoor environment pollution and signs or symptoms of dry eye disease in humans?" Dry eye disease is associated with air pollution (from NO2) and soil pollution (from chromium), but not from air pollution from CO or PM10. Future research should adequately account for confounders, follow up over time, and report results separately for ocular surface findings, including signs and symptoms.

Climatic Droplet Keratopathy Is a Misnomer for This Corneal Degeneration

PURPOSE

To describe a new insight into the Climate Droplet Keratopathy (CDK) pathophysiology and its major predisposing factors.

METHOD

A literature search was undertaken on PubMed to compile papers published on CDK. The following is a focused opinion tempered by synthesis of current evidence, and research of the authors.

RESULTS

CDK is a multifactorial rural disease common in regions with high incidence of pterygium, but not related to the type of climate or ozone concentrations. Although it has been thought that climate is the cause of this disease, recent investigations deny that and reveal that other environmental factors such as dietary intake, eye protection, oxidative stress, and ocular inflammatory pathways play an important role in the pathogenesis of CDK.

CONCLUSION

Considering the negligible effect of climate, the present name " CDK" for this illness can be confusing for young ophthalmologists. Based on these remarks, it is imperative to start using an accurate name like "Environmental Corneal Degeneration (ECD)" that fits the most recent evidence related to its etiology.

Prevalence and associated factors for climatic droplet keratopathy in Kazakhs adults: a cross-sectional study in Tacheng, Xinjiang, China

Background

Investigation of the prevalence of climatic droplet keratopathy (CDK) in Tacheng, Xinjiang, China.

Methods

A total of 1030 participants, in their 40s or older, from the Kazakh ethnic group in Tacheng, were randomly sampled by stratification method. Ophthalmic examinations and surveys were carried out on these participants. Factors associated with CDK were analyzed with logistic regression models.

Results

CDK was found in 66 (6.4%; 95% confidence interval [CI]: 4.9–7.9%) Kazakh individuals.

After multiple regression model analysis, it demonstrated that age (< 0.001), exposure time (< 0.001), exposure protection (< 0.001), and vegetable intake (< 0.001) were of correlation with CDK, of which age (OR = 1.21[CI]: 1.16–1.27) and long-term outdoor exposure (OR = 2.42[CI]: 1.26–4.67) were the risk factors, and that vegetable intake (OR = 0.29[CI]: 0.14–0.59) and wearing a hat (OR = 0.24[CI]: 0.10–0.56) were protective factors.

Conclusions

This study has revealed the risk and protective factors of CDK, providing a new insight on related research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02065-4.

Phospholipidomic Studies in Human Cornea From Climatic Droplet Keratopathy

Climatic droplet keratopathy (CDK) is an acquired degenerative disease predominantly affecting males over 40 years old. It results in progressive corneal opacities usually affecting both eyes. CDK is multifactorial and its etiology remains unknown. Our recent findings are consistent with CDK pathology being driven by environmental factors with oxidative stress playing an important role (e.g.,, contributing to lipid peroxidation) rather than climate factors. The changes in corneal lipid composition affected by environmental factors remain understudied. The purpose of this study was to systematically investigate phospholipids profile (phosphatidylcholine [PC] and phosphatidylserine [PS]) in corneas from CDK patients using tandem mass spectrometry. Samples from CDK areas and from non-affected areas were obtained from patients diagnosed with CDK who underwent cataract surgery, were subjected to lipid extraction using a modified Bligh and Dyer method; protein concentrations were determined using the Bradford's method. Lipids were identified and subjected to ratiometric quantification using TSQ Quantum Access Max triple quadrupole mass spectrometer, using appropriate class specific lipid standards. All phospholipid classes showed lower total amounts in affected areas compared to control areas from CDK's corneas. Comparative profiles of two phospholipid classes (PC, PS) between CDK areas and control areas showed several common species between them. We also found a few unique lipids that were absent in CDK areas compared to controls and vice versa. Lower amount of phospholipids in CDK areas compared to control areas could be attributed to the lipid peroxidation in the affected corneal regions as a consequence of increased oxidative stress. J. Cell. Biochem. 118: 3920-3931, 2017. © 2017 Wiley Periodicals, Inc.

Climatic Droplet Keratopathy in Argentina: Involvement of Environmental Agents in Its Genesis Which Would Open the Prospect for New Therapeutic Interventions

Climatic droplet keratopathy (CDK) is a degenerative corneal disease of unknown etiology. We described CDK for the first time in Latin America in the Argentinean Patagonia (El Cuy). A deeper knowledge of CDK pathogenic mechanisms will provide new therapeutic strategies. For that reason we investigated the prevalence of CDK in El Cuy and its existence in other 3 provinces with similar climate. Patients eyes were examined, habits throughout lives were inquired about, and serum ascorbate (sAA) was determined. All individuals work outdoors for most of the day. All regions had normal O₃ levels. Individuals from regions 1, 2, and 3 had very low consumption of vegetables/fruits and low sAA levels. Conversely, region 4 individuals had balanced diet and higher sAA concentrations. CDK was only found in region 3 where individuals had partial deficiency of sAA and did not use eye protection. No CDK was found in regions 1 and 2 where individuals had similar work activities and dietary habits to those in region 3 but wear eye protection. No disease was found in region 4 where individuals work outdoors, have balanced diet, and use eye protection. To summarize, the CDK existence was related not only to climate but also to the dietary habits and lack of protection from sunlight.

Climatic droplet keratopathy: an old disease in new clothes

Climatic droplet keratopathy (CDK) is an acquired and potentially handicapping cornea degenerative disease that is highly prevalent in certain rural communities around the world. It predominantly affects males over their forties. It has many other names such as Bietti's band-shaped nodular dystrophy, Labrador keratopathy, spheroidal degeneration, chronic actinic keratopathy, oil droplet degeneration, elastoid degeneration and keratinoid corneal degeneration. CDK is characterized by the haziness and opalescence of the cornea's most anterior layers which go through three stages with increasing severity. Globular deposits of different sizes may be histopathologically observed under the corneal epithelium by means of light and electron microscopy. The coalescence and increased volume of these spherules may cause the disruption of Bowman's membrane and the elevation and thinning of the corneal epithelium. The exact aetiology and pathogenesis of CDK are unknown, but they are possibly multifactorial. The only treatment in CDK advanced cases is a corneal transplantation, which in different impoverished regions of the world is not an available option. Many years ago, the clinical and histological aspects of this disease were described in several articles. This review highlights new scientific evidence of the expanding knowledge on CDK's pathogenesis which will open the prospect for new therapeutic interventions.

Effects produced by different types of laser in cornea of Guinea pigs: Identification of a laser capable of producing superficial lesions without leaving scars

PURPOSE

Climatic droplets keratopathy (CDK) is closely associated with superficial corneal erosions and lack of protective mechanisms against the harmful effects of ultraviolet radiation (UVR) during a prolonged period of time. One of the difficulties in studying the pathogenic mechanisms involved in this human disease is the lack of an experimental animal model. In this paper, a study is conducted on the effects of 4 types of lasers at various powers and time conditions on the normal guinea pig corneas in order to select only one laser condition that reversibly injures the epithelium and superficial stroma, without leaving scarring.

METHODS

Damage was induced in the cornea of Guinea pigs using different powers and exposure times of 4 types of laser: argon, CO2, diode and Nd-Yag, and any injuries were evaluated by biomicroscopy (BM) and optical microscopy. Corneas from other normal animals were exposed to argon laser (350 mW, 0.3s, 50 μm of diameter), and the induced alterations were studied at different times using BM, optical coherence tomography (OCT) and transmission electron microscopy (TEM).

RESULTS

Only argon laser at 350 mW, 0.3s, 50 μm of diameter produced epithelium and superficial stroma lesions. Some leukomas were observed by BM, and they disappeared by day 15. Corneal thickness measured by OCT decreased in the eyes treated with argon laser during the first week. Using TEM, different ultra structural alterations in corneal epithelium and stroma were observed during the early days, which disappeared by day 15.

CONCLUSIONS

It was possible to develop reproducible corneal epithelium and anterior stroma injuries using Argon laser at 350 mW, 0.3s, 50 μm of diameter. In vivo and in vitro studies showed that injured corneas with these laser conditions did not leave irreversible microscopic or ultra structural alterations. This protocol of corneal erosion combined with exposure to UVR and partial deficiency of ascorbate in the diets of the animals for an extended period of time has been used in order to try to develop an experimental model of CDK.

Prevalence of Punctate Keratopathy of West Indians in a Colombian Referral Center and a New Name Proposed: Rice´s Keratopathy

Purpose :

To perform a prevalence study of Punctate Keratopathy of West Indians in Colombian individuals and to propose a new name for the condition.

Methods :

Prospective, population-based epidemiological study. All patients evaluated between November 1 and December 31, 2012, in the Centro Oftalmológico Virgilio Galvis and Fundación Oftalmológica de Santander (FOSCAL), Floridablanca, Colombia, with clinical findings of white corneal opacities corresponding to Punctate Keratopathy of West Indians were identified. Careful slit-lamp examination was performed for clinical diagnosis and findings were reported in the electronic medical record indicating number and location of the lesions. Prevalence was calculated for the total population, and for gender and age groups. Furthermore a literature review was performed and a new name for the condition proposed.

Results :

In the whole group of patients, prevalence was 1.0%. No one case was diagnosed in a patient younger than 21 year-old. No one lesion was located within 2.5 mm of the corneal apex. 96% of affected patients had unilateral involvement. 58.5% of eyes had a single corneal lesion; 7% of eyes had 6 or 7 corneal lesions.

Conclusion :

The condition heretofore known as Punctate Keratopathy of West Indians was present in 1% of our patients in Colombia (South America). Thus, this non-infectious, non-inflammatory, asymptomatic ailment of unknown etiology is not restricted to people of Antillean descent, or who have lived in these islands. We propose the new name “Rice's keratopathy". Age and male gender were independent risk factors for the presence of the keratopathy.

Ocular morbidity among refugees in Southwest Ethiopia

BACKGROUND

Low vision and blindness are recognized as one of the major public health problems worldwide, especially in developing countries. The prevalence and cause of blindness and low vision vary from region to region, among different age and population groups in a country or geographical region. The objective of this study is thus to determine the causes of blindness and ocular morbidity among refugees in Southwest Ethiopia.

METHODS

A cross-sectional clinic based study was conducted on 1,054 refugees in Southwest Ethiopia. A basic anterior and posterior segment examination was done by ophthalmologists with Magnifying Loupe 2.5X and Direct Ophthalmoscope. Data were analyzed using SPSS version 16.0.

RESULTS

The most common causes of ocular morbidity identified were trachoma 547(21.2%), cataract 501(19.4%), refractive error 353(13.7%), conjunctivitis 240(9.3%), glaucoma 130(5.1%) and climatic droplet keratopathy 112(4.4%). The overall prevalence of blindness was 26.2% and the prevalence of childhood blindness was 0.7%. The prevalence was higher among females (16.9%) than males (9.3%) and age groups 60 years and above (15.9%) than other age groups (10.3%) (P<0.05). The overall prevalence of low vision was 25.8% and the prevalence of low vision in pediatric age group was 0.9%. The leading causes of blindness were cataract 112(40.6%), trachomatous corneal opacity 58(21.0%) and glaucoma 49(17.8%). The commonest cause of low vision was cataract 102(37.6%) followed by trachomatous corneal opacity 49(18.1%) and refractive error 35(12.9%).

CONCLUSIONS

There is a very high burden of blinding eye diseases among refugees. Integrated multidisciplinary intervention strategies for the prevention and control of blindness and low vision in the study settings should be initiated.

Genetic background and climatic droplet keratopathy incidence in a Mapuche population from Argentina

Purpose

To determine whether the incidence of and susceptibility to climatic droplet keratopathy (CDK), an acquired, often bilateral degenerative corneal disease, is influenced by the genetic background of the individuals who exhibit the disorder.

Methods

To determine whether the disease expression was influenced by the genetic ancestry of CDK cases in native Mapuche of the northwest area of Patagonia in Argentina, we examined mitochondrial DNA and Y-chromosome variation in 53 unrelated individuals. Twenty-nine of them were part of the CDK (patient) population, while 24 were part of the control group. The analysis revealed the maternal and paternal lineages that were present in the two study groups.

Results

This analysis demonstrated that nearly all persons had a Native American mtDNA background, whereas 50% of the CDK group and 37% of the control group had Native American paternal ancestry, respectively. There was no significant difference in the frequencies of mtDNA haplogroups between the CDK patient and control groups. Although the Y-chromosome data revealed differences in specific haplogroup frequencies between these two groups, there was no statistically significant relationship between individual paternal genetic backgrounds and the incidence or stage of disease.

Conclusions

These results indicate a lack of correlation between genetic ancestry as represented by haploid genetic systems and the incidence of CDK in Mapuche populations. In addition, the mtDNA appears to play less of a role in CDK expression than for other complex diseases linked to bioenergetic processes. However, further analysis of the mtDNA genome sequence and other genes involved in corneal function may reveal the more precise role that mitochondria play in the expression of CDK.

Altered expression of matrix metalloproteinases and their tissue inhibitors as possible contributors to corneal droplet formation in climatic droplet keratopathy

PURPOSE

Climatic droplet keratopathy (CDK) is an acquired corneal disease characterized by progressive scarring of the cornea. In several corneal diseases, matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation and molecular forms of MMP-2, MMP-9, MMP-8 and MMP-13 and their tissue inhibitors TIMP-1 and TIMP-2 in tear fluid of patients with CDK.

METHODS

Seventeen CDK patients and 10 controls living in Argentine Patagonia received a complete eye examination, and MMPs and TIMP-1/2 were determined by immunofluorometric assay (IFMA), gelatin zymography and quantitative Western immunoblot analysis in tear samples.

RESULTS

The MMPs were detected mostly in their latent forms. The levels of MMP-9 and MMP-2 were found to be significantly elevated in CDK patients, whereas latent and active MMP-8 levels were significantly enhanced in controls. There was no significant difference in the level of MMP-13. TIMPs were found as part of complexes, and the TIMP-1 levels were significantly lower in patients than controls.

CONCLUSION

Elevated MMP-2 and MMP-9 levels have been implicated in the failure of corneal re-epithelialization, and enhanced MMP-2 and MMP-9 levels in CDK patients suggest that these MMPs may play a role in corneal scarring in CDK. Elevated levels of MMP-8 suggest a defensive role for this MMP in inflammatory reactions associated with recurring corneal traumas. Decreased expression of TIMP-1 in CDK patients suggest deficient antiproteolytic shield likely to render the corneas of CDK patients vulnerable to enhanced MMPs. Overall, these data suggest a mechanistic link between MMPs and TIMP-1 level in cornea and tears with corneal scarring in CDK.

Distribution of conjunctival ultraviolet autofluorescence in a population-based study: the Norfolk Island Eye Study

OBJECTIVE

The objective of this study was to describe the distribution of conjunctival ultraviolet autofluorescence (UVAF) in an adult population.

METHODS

We conducted a cross-sectional, population-based study in the genetic isolate of Norfolk Island, South Pacific Ocean. In all, 641 people, aged 15 to 89 years, were recruited. UVAF and standard (control) photographs were taken of the nasal and temporal interpalpebral regions bilaterally. Differences between the groups for non-normally distributed continuous variables were assessed using the Wilcoxon-Mann-Whitney ranksum test. Trends across categories were assessed using Cuzick's non-parametric test for trend or Kendall's rank correlation τ.

RESULTS

Conjunctival UVAF is a non-parametric trait with a positively skewed distribution. Median amount of conjunctival UVAF per person (sum of four measurements; right nasal/temporal and left nasal/temporal) was 28.2 mm(2) (interquartile range 14.5-48.2). There was an inverse, linear relationship between UVAF and advancing age (P<0.001). Males had a higher sum of UVAF compared with females (34.4 mm(2) vs 23.2 mm(2), P<0.0001). There were no statistically significant differences in area of UVAF between right and left eyes or between nasal and temporal regions.

CONCLUSION

We have provided the first quantifiable estimates of conjunctival UVAF in an adult population. Further data are required to provide information about the natural history of UVAF and to characterise other potential disease associations with UVAF. UVR protective strategies should be emphasised at an early age to prevent the long-term adverse effects on health associated with excess UVR.

Surface Alterations, Corneal Hypoesthesia, and Iris Atrophy in Patients With Climatic Droplet Keratopathy

PURPOSE

To present external eye findings and the observation of iris atrophy in patients with climatic droplet keratopathy (CDK).

METHODS

Twenty-three patients with CDK and 13 controls living in a semideserted plain of the Argentine Patagonia were studied. Besides a comprehensive eye examination, Cochet-Bonnet aesthesiometry, Schirmer II test, breakup time (BUT), and surface staining were performed. According to corneal findings, eyes were grouped as grade 1 (confluent translucent microdroplets localized in the limbic region of the horizontal quadrants); grade 2 (band-shaped subepithelial haziness compromising the central cornea); and grade 3 (previously described lesions with yellow subepithelial droplets). Results were analyzed with the Fisher, Mann-Whitney, and Spearman tests, which were considered significant at P < 0.05.

RESULTS

Nineteen of 23 patients with CDK had bilateral disease, which was asymmetric in 2 of them. Sixteen eyes had grade 1, 21 eyes had grade 2, and 5 eyes had grade 3 disease. Aesthesiometry showed that the more advanced the disease, the more profound the corneal hypoesthesia (P = 0.0008). BUT and ocular surface staining significantly differed between eyes with grade 3 and grade 1, grade 3 and grade 2, and grade 3 and controls. In 38.09% of eyes with CDK and in none of the controls, sectorial depigmentation and atrophy of the inferior iris were observed.

CONCLUSIONS

A severe decrease of corneal sensitivity was observed in advanced stages of CDK. Some degree of dry eye was present in most patients, but severe disease was infrequent at any stage of CDK. Inferior iris depigmentation and atrophy was frequently observed among patients with CDK.