Eye Color Research Articles

Pioneering genome editing in parthenogenetic stick insects: CRISPR/Cas9-mediated gene knockout in Medauroidea extradentata

The parthenogenetic life cycle of the stick insect Medauroidea extradentata offers unique advantages for the generation of genome-edited strains, as an isogenic and stable mutant line can in principle be achieved already in the first generation (G0). However, genetic tools for the manipulation of their genes had not been developed until now. Here, we successfully implement CRISPR/Cas9 as a technique to modify the genome of the stick insect M. extradentata. As proof-of-concept we targeted two genes involved in the ommochrome pathway of eye pigmentation (cinnabar and white, second and first exon, respectively), to generate knockout (KO) mutants. Microinjections were performed within 24 h after oviposition, to focus on the mononuclear (and haploid) stage of development. The KOs generated resulted in distinct eye and cuticle colour phenotypes for cinnabar and white. Homozygous cinnabar mutants showed pale pigmentation of eyes and cuticle. They develop into adults capable of producing viable eggs. Homozygous white KO resulted in a completely unpigmented phenotype in developing embryos that were unable to hatch. In conclusion, we show that CRISPR/Cas9 can be successfully applied to the genome of M. extradentata by creating phenotypically different and viable insects. This powerful gene editing technique can now be employed to create stable genetically modified lines using a parthenogenetic non-model organism.

Comprehensive Morphological Characterization of Cowpea (Vigna unguiculata (L.) Walp.) Genotypes for Enhanced Breeding Programs in Jammu and Kashmir

Cowpea (Vigna unguiculata (L.) Walp.) is an important legume crop that is recognized for its adaptability to diverse climates and nutritional value. In Jammu and Kashmir, however, its genetic diversity is limited, hindering full yield potential. This study aimed to characterize 72 cowpea genotypes from various regions of Kashmir through Distinctness, Uniformity, and Stability (DUS) characterization. Twenty-four agro-morphological traits were assessed following the guidelines of the Protection of Plant Varieties and Farmers' Rights Authority (PPV&FRA). Key traits, such as stem color, flowering time, pod length, growth habit, and seed characteristics, were evaluated for distinctness and breeding value. The analysis identified promising genotypes such as C15 (medium seed length and black eye color), CP23-3 (high pod count), C32 (spreading growth and late maturity), TPTC-29 (early flowering, erect growth), C28 (tan eye color, medium seed size), and KDC-39 (high seed count per pod, late flowering). The genotypes exhibited favorable traits, such as early flowering, robust growth, strong pod attachment, and varied maturity, supporting breeding programs aimed at improving cowpea yield and adaptability in climate-stressed regions.

Development and Validation of the Asian AMD Age-Related Macular Degeneration Risk Scale

Introduction: This study aimed to develop a method for predicting the risk of developing macular degeneration in the early stages by facilitating prompt intervention by medical professionals. Methods: Using a cross-sectional design, 455 age-related macular degeneration (AMD) patients from Kazakhstan were recruited via random sampling. Demographic traits, familial AMD history, medical history, and eye-related characteristics were collected through a systematic questionnaire. The patient cohort comprised 169 Caucasians and 286 Asians, with 160 males and 295 females. Results: Notably, 117 individuals (25.7%) were classified as high AMD risk, 322 (70.8%) as moderate risk, and 16 (3.5%) as low risk. Additionally, eye-related findings revealed high-risk factors, including bright iris colors, increased UV exposure, and cataract surgery, alongside presbyopia and myopia. The study underscores the need for national/regional AMD risk stratification to inform monitoring and screening programs. Recognizing high-risk individuals holds paramount significance from both public health and therapeutic perspectives, offering opportunities for early detection and management to mitigate permanent vision loss. Conclusions: The findings elucidate the interplay between risk factors, shedding light on their collective impact on AMD risk. Overall, this study's predictive model and risk categorization framework have substantial implications for ophthalmological practice, enabling timely preventive measures and potentially revolutionizing AMD management.

Development and Validation of the Asian AMD Age-Related Macular Degeneration Risk Scale

Introduction: This study aimed to develop a method for predicting the risk of developing macular degeneration in the early stages by facilitating prompt intervention by medical professionals. Methods: Using a cross-sectional design, 455 age-related macular degeneration (AMD) patients from Kazakhstan were recruited via random sampling. Demographic traits, familial AMD history, medical history, and eye-related characteristics were collected through a systematic questionnaire. The patient cohort comprised 169 Caucasians and 286 Asians, with 160 males and 295 females. Results: Notably, 117 individuals (25.7%) were classified as high AMD risk, 322 (70.8%) as moderate risk, and 16 (3.5%) as low risk. Additionally, eye-related findings revealed high-risk factors, including bright iris colors, increased UV exposure, and cataract surgery, alongside presbyopia and myopia. The study underscores the need for national/regional AMD risk stratification to inform monitoring and screening programs. Recognizing high-risk individuals holds paramount significance from both public health and therapeutic perspectives, offering opportunities for early detection and management to mitigate permanent vision loss. Conclusions: The findings elucidate the interplay between risk factors, shedding light on their collective impact on AMD risk. Overall, this study's predictive model and risk categorization framework have substantial implications for ophthalmological practice, enabling timely preventive measures and potentially revolutionizing AMD management.

Genome assembly of a nocturnal butterfly (Macrosoma leucophasiata) reveals convergent adaptation of visual genes

Nearly all animals exhibit a preferred period of daily activity (diel-niche), strongly influenced by the light environment. Vision is a sensory system that is strongly adapted to light, and evolutionary transitions to novel light environments can impose strong constraints on eye evolution, color, and motion vision. While the genetic and neural basis of visual adaptation are well-studied in a few model systems, our understanding across the tree of life remains incomplete. Butterflies and moths are an ideal system to investigate the association between gene evolution and diel-niche transitions. While most butterflies are day-flying, hedylid butterflies are unique in being primarily nocturnal, representing an important evolutionary shift from diurnality to nocturnality. We sequenced the first Hedylidae genome and annotated it to understand genomic changes associated with diel niche shifts. Comparing Hedylidae visual genes to those of other diurnal and nocturnal Lepidoptera revealed that visual genes are highly conserved, with no major losses. However, hedylid opsins were more similar to nocturnal moths than their diurnal congeners, suggesting that these opsins convergently evovled to adapt to the nocturnal environment. Evolutionary rate tests (dN/dS) confirmed strong selection on color vision opsins, with some sites being mapped to the functional domain of the blue opsin. Our study provides new insight into the molecular evolutionary adaptations associated with species’ changes to new light environments.

AN AYURVEDIC APPROACH IN THE MANAGEMENT OF KAMALA W.S.R. TO JAUNDICE: A SINGLE CASE STUDY

INTRODUCTION: Kamala is both raktapradoshaja vyadhi and pittaja nanatmaja. According to Charakacharya, kamala is a more advanced level of panduroga. While Vagbhatacharya described kamala as a distinct ailment, Sushrutacharya considered it a separate disease that might be caused by a further panduroga problem. In con-temporary medicine, kamala is associated with jaundice. Vyadhi Aacharyas have described Virechana Karma in Kamala. The limitations of modern science in treating Kamala Vyadhi (jaundice) are evident in the Ayurvedic literature, which elucidates the etiology and therapy of the condition and highlights the peculiarity of Ayurveda. The majority of individuals have grown accustomed to spicy fast food over time. Humanity has been separated from nature by this. The intake of alcohol is likewise rising daily in the modern day. Hepatocellular jaundice is referred to in Ayurvedic writings as Kamala. "Kamali tu virechanama" has also been cited by ancient Acharyas as the Chikitsa Sutra for Kamala. AIMS AND OBJECTIVES To find out the effect of Ayurvedic medicine in the management of Kamala (Jaundice) managed with Shaman chikitsa. MATERIAL AND METHODES A 15yr. Old girl patient came with the complaint of Anorexia, Urine -Pale yellow, Ab-dominal pain after taking of food, Face yellow, and yellowish coloration of eyes and nails. The patient has taken medicine, but no relief was found, so she came to us for Ayurveda treatment. RESULT AND DISCUSSION The outcomes were noteworthy Regarding the clinical and analytical criteria. According to statistics, there is improvement in the yellowing of the urine and eyes, weakness, appetite loss, and serum bilirubin levels. 15-year-old girl came for Ayurvedic treatment for Kamala. We planned Sanshaman chikitsa.

Incidence, Damage and Management of the Major Pests and Diseases of Robusta Coffee, [Coffea canephora (Pierre Ex A. Froehner)] in Uganda

Black Coffee Twig Borer (BCTB), Xylosandrous compactus Eichhoff (Coleoptera: Scolytidae) and Coffee Wilt Disease (CWD) are still the two main biological constraints to Robusta coffee production in Uganda. A rapid assessment survey was conducted in January 2022 in the Regions of Eastern (Busoga), Greater Masaka, Western, South western and Rwenzori to determine the status of pests and diseases in the different regions. A short-structured questionnaire with both open and closed-ended questions was administered to 268 participants that were purposively selected in different regions. At plot level, five coffee plants were selected in each of the sampled coffee farms for observation. The selected stems were checked for infestation by the stem borers and root mealy bugs (evidenced by ants moving up and down the coffee tree). The coffee canopy was divided into 2 imaginary sections—upper and lower to assess damage by leaf skeletonizers, tailed caterpillars, beetles, aphids, mealybugs, lygus, brown eye spot, coffee leaf rust, scales, aphids, berry moth and red blister. In addition, data was collected at field level parameters including: shade intensity, the most common shade trees, weed management and most common weeds (whether grasses, sedges or broadleaved), mulching intensity and mulching material, manuring intensity and common manure used, fertilizer application and type of fertilizer used, presence and type of cover crops, presence of bands and trenches as well as intensity of intercropping and the most common intercrops. Field observations revealed that the Black Coffee Twig Borer (BCTB) was responsible for the drying up of young and old coffee branches across all regions together with Coffee Wilt disease (CWD) to a smaller extent. On average, 9.4% of the primary branches were infested by BCTB. The highest damage levels of BCTB were recorded in Eastern (17.2%) and Western (12.4%) regions. Although, BCTB affected all ages of coffee, young coffee of 2-3 years was most affected. Overall, 3.9% of the sampled coffee trees were infected by Coffee Wilt Disease (CWD), with the highest incidence (8.2%) recorded in Southwestern Uganda. There is need to enhance existing management measures for coffee pests and diseases especially BCTB and CWD. Due to the high levels of spread of BCTB, this will require a community approach to sensitize farmers through meetings and media on the sustainable management of BCTB. There is also need to come up with good dissemination strategies of Coffee Wilt Disease Resistant varieties to aid their uptake and roll out a gap filling programme for coffee trees infected and destroyed by CWD across all regions using CWDr varieties.

Comparison of the Sensory Quality of Fresh and Steamed Organic Tilapia

This study aimed to evaluate the sensory attributes of steamed and fresh organic tilapia and determine the acceptability of both preparations among consumers. Fifty respondents, aged 15-60 years, participated in the sensory evaluation. The organic tilapia used in the study was of the GET ExCEL 2010 strain, harvested with an average weight of 60-100 grams after a four-month culture period. Both steamed and fresh tilapia were assessed for five sensory attributes: shininess of scales, color of eyes, color of gills, odor, and firmness. The sensory evaluation was conducted using a consumer preference test, and statistical analysis was performed using descriptive statistics and paired t-tests. The results indicated that both steamed and fresh tilapia were generally well-accepted, with no significant differences in sensory attributes between the two preparations (p-value > 0.05). Steamed tilapia scored higher in odor, with a mean of 8.0, "Like Very Much," while fresh tilapia received slightly lower scores in visual attributes such as shininess of scales and color of eyes. However, both forms maintained moderate acceptability in terms of odor and gill color, key indicators of freshness. The findings suggest that organic tilapia, regardless of preparation method, offers a consistent sensory experience, making it a versatile and appealing option for consumers. This study highlights the potential of organic tilapia as a sustainable and high-quality freshwater fish choice in the market.

Eye colour is geographically variable in Lesser Roadrunner Geococcyx velox (Wagner, 1836)

Eye colour is geographically variable in Lesser Roadrunner Geococcyx velox (Wagner, 1836)

Assessing chromatic discrimination in individuals varying in iris color and ethnic origin

Assessing chromatic discrimination in individuals varying in iris color and ethnic origin

Interchromosomal contacts between regulatory regions trigger stable transgenerational epigenetic inheritance in Drosophila.

Non-genetic information can be inherited across generations in a process known as transgenerational epigenetic inheritance (TEI). In Drosophila, hemizygosity of the Fab-7 regulatory element triggers inheritance of the histone mark H3K27me3 at a homologous locus on another chromosome, resulting in heritable epigenetic differences in eye color. Here, by mutating transcription factor binding sites within the Fab-7 element, we demonstrate the importance of the proteins pleiohomeotic and GAGA factor in the establishment and maintenance of TEI. We show that these proteins function by recruiting the polycomb repressive complex 2 and by mediating interchromosomal chromatin contacts between Fab-7 and its homologous locus, respectively. Using an invivo synthetic biology system to induce them, we then show that chromatin contacts alone can establish TEI, providing a mechanism by which hemizygosity of one locus can establish epigenetic memory at another distant locus in trans through chromatin contacts.

Assessment of phenotypic diversity and morphometry of indigenous chickens in Kabwe District, Zambia

This study characterized Zambian indigenous chickens' phenotypes and morphometric traits in Kabwe District, Zambia, to create a base for breeding program development. To achieve this, 206 hens and 228 cocks we sampled in Kabwe district. Each sampled chicken was phenotyped for 4 qualitative traits: ear lobe color, shank color, comb type, and eye color. Individual linear body measurements were recorded from each chicken using a tailor's tape in centimeters, which included body length (BL), chest circumference (CC), corpus length (CL), keel length (KL), shank circumference (SC), shank length (SL), thigh circumference (TC), and thigh length (TL). The findings showed that the predominant phenotypes were single comb type (98.91%), orange eyes (80.44%), white shanks (33.70%), and red-white earlobe color (50%). The average body weight was 1698.24 g, which showed a significant positive correlation (p<0.05) with all linear body measurements. For both sexes, body weight correlated positively with all linear measurements, except in males where body length showed a nonsignificant negative correlation. A stepwise regression analysis indicated that chest circumference, keel length, body length, shank circumference, thigh circumference, and corpus length (CL) are significant predictors of body weight (R² = 76.90%, P < 0.05). Additionally, the CHAID data mining algorithm identified keel length as the primary predictor of body weight, with corpus length and thigh length also contributing, achieving an R² of 61.20%. These findings provide valuable insights for instituting chicken breeding programs aimed at enhancing productivity and selection decisions.

Collection of dna and the Creation of dna Databases in India: A Proportionality Analysis on Whether There is a Violation of Genetic Privacy

Abstract Genetic information, which can be processed from human bodily samples, contains three major types of information: first, individual traits such as the skin colour, race, eye colour, and height of the data subject; second, medical information such as information about genetic diseases and genetic predispositions; and third and most importantly, it can provide information about a class of persons who are genetically related to the data subject. Genetic data has huge application potential, from criminal investigations to assisted reproductive techniques. Thus, it is the most sensitive form of personal data. The concept of privacy in India has also evolved by way of judicial pronouncements and, in the case of K.S. Puttaswamy v Union of India, it was recognised as a fundamental right. The Indian Government has passed the Criminal Procedure Identification Act, 2022, which allows for the collection of measurements – including genetic samples – and authorises the National Crime Records Bureau to collect, store, process, share, and disseminate such data. In light of the above developments, this article analyses the constitutionality of section 3 of the Criminal Procedure Identification Act, 2022 through the lens of the principle of proportionality.

Single Nucleotide Polymorphisms on Toll-like Receptor-4 and the Risk of Developing Skin Cancer.

Exposure to solar ultraviolet (UV) radiation is an established risk factor for skin cancer. Toll-like receptor-4 (TLR4)-mediated immune dysregulation has emerged as a key mechanism for the detrimental effects of acute and chronic UV exposure and skin cancer in mice. Single nucleotide polymorphisms (SNPs) on the TLR4 gene have been reported to increase or decrease susceptibility to various cancers in other organs. There is limited information on TLR4 SNPs and susceptibility to human keratinocyte carcinomas. The study's objective is to test the association between TLR4 SNPs and the risk of developing keratinocyte carcinomas. Skin cancer patients and controls at the University of Alabama at Birmingham completed a cross-sectional survey on personal and family history of skin cancer as well as on sunscreen use and tanning proneness. Peripheral blood samples were obtained from participants, and DNA was extracted to genotype the TLR4 SNPs. Descriptive analytics were used to describe the cohort. Multivariable logistic regression models were used to assess the association between TLR4 SNPs and skin cancer risk. The sample consisted of a cohort of 93 skin cancer patients over the age of 50 and 94 controls; 33.3% of cases and 44.7% of controls were females; 12.9% of cases and 17% of controls had a TLR4 SNP. The most common SNP was D299G/T399I in 9.7% of skin cancer patients and 13.8% of controls. We did not find a statistically significant association between the D299G/T399I SNP and skin cancer (odds ratio (OR) = 0.34, 95% CI: 0.11, 1.07, p = 0.065) adjusting for age, sex, eye color, actinic keratosis, sunscreen use and reapplication, and family history of skin cancer. Based on our findings from our limited cohort of participants, we found some protective effect for the TLR4 SNP for skin cancer, which was not statistically significant. Validation of these findings in a larger cohort is warranted.

Influencing Factors on Pupillary Light Responses as a Biomarker for Local Retinal Function in a Large Normative Cohort.

Investigating influencing factors on the pupillary light response (PLR) as a biomarker for local retinal function by providing epidemiological data of a large normative collective and to establish a normative database for the evaluation of chromatic pupil campimetry (CPC). Demographic and ophthalmologic characteristics were captured and PLR parameters of 150 healthy participants (94 women) aged 18 to 79 years (median = 46 years) were measured with L-cone- and rod-favoring CPC protocols. Linear-mixed effects models were performed to determine factors influencing the PLR and optical coherence tomography (OCT) data were correlated with the pupillary function volume. Relative maximal constriction amplitude (relMCA) and latency under L-cone- and rod-favoring stimulation were statistically significantly affected by the stimulus eccentricity (P < 0.0001, respectively). Iris color and gender did not affect relMCA or latency significantly; visual hemifield, season, and daytime showed only minor influence under few stimulus conditions. Age had a statistically significant effect on latency under rod-specific stimulation with a latency prolongation ≥60 years. Under photopic and scotopic conditions, baseline pupil diameter declined significantly with increasing age (P < 0.0001, respectively). Pupillary function volume and OCT data were not correlated relevantly. Stimulus eccentricity had the most relevant impact on relMCA and latency of the PLR during L-cone- and rod-favoring stimulation. Latency is prolonged ≥60 years under scotopic conditions. Considering the large study collective, a representative normative database for relMCA and latency as valid readout parameters for L-cone- and rod-favoring stimulation could be established. This further validates the usability of the PLR in CPC as a biomarker for local retinal function.

Photoregulatory functions drive variation in eye coloration across macaque species

Primates, the most colorful mammalian radiation, have previously served as an interesting model to test the functions and evolutionary drivers of variation in eye color. We assess the contribution of photo-regulatory and communicative functions to the external eye appearance of nine macaque species representing all the branches of their radiation. Macaques’ well described social structure and wide geographical distribution make them interesting to explore. We find that (1) the posterior option of the anterior eyeball is more pigmented closer to the equator, suggesting photoprotective functions. We also find that (2) the temporal side of the eyeball is more heavily pigmented than the nasal side. This suggests that eyeball pigmentation in macaques is distributed to reduce damage to the corneal limbus. The inclusion of a translocated population of M. fuscata in our analyses also suggests that external eye appearance may change quickly, perhaps owing to phenotypic plasticity. We find no evidence that communicative functions drive variation in external eye appearance in macaques. These results suggest that the amount of light in a species’ environment drives variation in eye coloration across macaque species. Furthermore, the geographical distribution of macaques hints at important factors that have yet to be accounted for, such as the reflectivity of the terrain a given species inhabits.

A comparison of cycloplegic effect of cyclopentolate 0.5% versus 1.0% eye drops with five different refraction measurement modalities in young adults.

To compare the refraction before and after cycloplegia with 0.5% and 1.0% cyclopentolate eye drops using five different measurement modalities. This prospective, clinical comparative study enrolled 96 eyes of 48 healthy patients with a mean age of 26.6 ± 4.21years (range: 19-34). Subjective refraction, retinoscopy, and objective refraction were measured using three autorefractometers: Topcon KR-800 (TC), Retinomax K-plus 3 (RM + 3), and Retinomax K-plus Screeen (RM + S) under noncycloplegic and cycloplegic conditions. Cycloplegia was performed in the right eye using 0.5% and in the left eye with 1.0% cyclopentolate eye drops. Differences in refraction in noncycloplegia and cycloplegia, between cycloplegia with 0.5% and 1.0% cyclopentolate, and between the devices were investigated. Cycloplegic mean spherical equivalent was -1.77 ± 2.34 diopters (D) (-9.75 to + 1.625). All approaches showed a statistically significant hyperopic shift (p < 0.001, each) after induction of cycloplegia using both regimes. Lowest median (interquartile range) hyperopic shift was shown by TC (0.25 D (0.38)) and retinoscopy (0.25D (0.75)), and the highest by RM + 3 (0.75 (1.31)). No statistically significant differences between cycloplegia using 0.5% and 1.0% regimens were shown in all modalities (p > 0.05, each). In noncycloplegia, there were greater differences compared to cycloplegia. No influence of iris color on the refraction was found. After induction of cycloplegia all devices showed a hyperopic shift and good comparability to retinoscopy. In all measurement modalities, no significant refraction differences between 0.5% and 1.0% cyclopentolate eye drops were seen. Therefore, 0.5% cyclopentolate was proven to have a sufficient effect with presumably better tolerability. What is known Cycloplegic refraction is a key test in the evaluation of any patient with active accommodation. The most frequently used clinical tests to determine the exact refraction are retinoscopy, subjective refraction, and objective refraction using autorefractometry. What is new No significant differences in the refraction between cycloplegia using 0.5% and 1.0% cyclopentolate eye drops were found. In noncycloplegia, hand-held autorefractometers tend to measure higher myopia. The evaluation of cycloplegic refraction showed good comparability between retinoscopy and subjective refraction as well as three different autorefractometers.

First record of a white phenotype Egyptian weasel (Mustela subpalmata) in Tahta, Sohag, Egypt

Abstract Aberrant pelage colourations have been occasionally detected in carnivores, including mustelids. However, to our knowledge, no cases of leucism have been reported in the genus Mustela to date. On May 1, 2024, an Egyptian weasel (Mustela subpalmata) killed by locals was discovered and photographed in the town of Tahta, Egypt. The specimen exhibited predominantly white fur on its left side and head. Although eye colour was not inspected, the normal lip colouration, dirty white fur hue, and dark brown tail tip suggest a case of leucism rather than albinism. Leucism is often linked to inbreeding caused by population isolation or size reduction, which could arise through urban development, considering that roads can act as social and physical barriers to gene flow. Genetic studies are needed to elucidate the population dynamics and conservation implications for urban Egyptian weasels.

L-cysteine gold nanoparticles for colorimetric and electrochemical detection of spermine and histamine

Biogenic amines (BAs) are metabolic products of living cells and have a pronounced impact on human physiological processes. They are also renowned food spoilage indicators as they are produced in higher quantities during food spoilage by bacteria. The higher concentration of these compounds in food can cause serious health concerns. Therefore, the detection of these compounds is of great significance. Herein, we developed a simple and rapid dual-mode colorimetric and an electrochemical method for detecting two representative BAs, i.e., spermine and histamine, using gold nanoparticles (AuNPs). The AuNPs were synthesized using the Turkevich method and functionalized with a simple molecule, L-Cysteine. The interaction of BAs with L-Cysteine-AuNPs demonstrates the naked eye color change at lower concentrations of BAs. The same L-Cysteine-AuNPs show enhanced electrochemical oxidation signals for histamine when immobilized on the surface of a glassy carbon electrode. The proposed detection method demonstrates the colorimetric changes from red to blue for the spermine concentration of 0.1–1 μM with a detection limit of 0.37 μM. Similarly, the colorimetric change was observed for histamine in the range of 1–10 μM concentration with a detection limit of 3.7 μM. In comparison, spermine is more sensitive at lower concentrations due to more binding sites forming stronger electrostatic interactions with the functionalized nanoparticles. The electrochemical oxidation signals were observed for histamine in the range of 5–60 μM with a detection limit of 11.1 μM. We demonstrate that the same functionalized nanoparticles remain sensitive to detecting histamine at higher concentrations despite the lack of pronounced colorimetric change.

The ever ongoing cosmetic quest to change eye colour.

To provide a historical overview of the various efforts to change eye colour for purely cosmetic reasons, along with the associated potential risks and harms. Literature and online search. Eye drops containing adrenaline were used during World War II on involuntary inmates of concentration camp Auschwitz-Birkenau. Prostaglandin drops, used in glaucoma therapy since 1996, can increase iris pigmentation as an undesired side effect. Commercial drops, available since 2011, are not effective and potentially dangerous. Iris implants, commercially available since 2011, led to serious complications like corneal decompensation, uveitis and glaucoma, and for this reason, implants had to be removed, leaving some patients almost blind. Also commercially in use since 2011 are laser treatments to make brown eyes blue. Among the possible complications are anterior uveitis and (pigmentary) glaucoma. Corneal tattooing has existed for almost 2000 years. Complications of modern, intrastromal keratopigmentation include corneal perforation, bacterial infection, allergic or toxic reaction to pigment, migration of pigment, and functional complications like visual field limitation and light sensitivity. Personal identity and self-esteem are likely contributing factors to undergo this potentially harmful cosmetic eye surgery. In addition to the earlier discussed complications, the artificial layer of colour can obscure ocular pathology of the cornea or iris. As the majority of individuals undergoing these procedures are relatively young, problems may arise in the future when they will need cataract or other eye surgeries. Permanently changing eye colour in healthy eyes for purely cosmetic reasons is a risky procedure.