A Systematic Review of Ophthalmology Education in Medical Schools: The Global Decline.

TOPIC: This systematic review examined geographical and temporal trends in medical school ophthalmology education in relationship to course and student outcomes. CLINICAL RELEVANCE: Evidence suggesting a decline in ophthalmology teaching in medical schools is increasing, raising concern for the adequacy of eye knowledge across the rest of the medical profession. METHODS: Systematic review of Embase and SCOPUS, with inclusion of studies containing data on medical school ophthalmic course length; 1 or more outcome measures on student ophthalmology knowledge, skills, self-evaluation of knowledge or skills, or student course appraisal; or both. The systematic review was registered prospectively on the International Prospective Register of Systematic Reviews (identifier, CRD42022323865). Results were aggregated with outcome subgroup analysis and description in relationship to geographical and temporal trends. Descriptive statistics, including nonparametric correlations, were used to analyze data and trends. RESULTS: Systematic review yielded 4596 publication titles, of which 52 were included in the analysis, with data from 19 countries. Average course length ranged from 12.5 to 208.7 hours, with significant continental disparity among mean course lengths. Africa reported the longest average course length at 103.3 hours, and North America reported the shortest at 36.4 hours. On average, course lengths have been declining over the last 2 decades, from an average overall course length of 92.9 hours in the 2000s to 52.9 hours in the 2020s. Mean student self-evaluation of skills was 51.3%, and mean student self-evaluation of knowledge was 55.4%. Objective mean assessment mark of skills was 57.5% and that of knowledge was 71.7%, compared with an average pass mark of 66.7%. On average, 26.4% of students felt confident in their ophthalmology knowledge and 34.5% felt confident in their skills. DISCUSSION: Most evidence describes declining length of courses devoted to ophthalmology in the last 20 years, significant student dissatisfaction with courses and content, and suboptimal knowledge and confidence. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Exploring the relationship between 24-2 visual field and widefield optical coherence tomography data across healthy, glaucoma suspect and glaucoma eyes.

PURPOSE: To utilise ganglion cell-inner plexiform layer (GCIPL) measurements acquired using widefield optical coherence tomography (OCT) scans spanning 55° × 45° to explore the link between co-localised structural parameters and clinical visual field (VF) data. METHODS: Widefield OCT scans acquired from 311 healthy, 268 glaucoma suspect and 269 glaucoma eyes were segmented to generate GCIPL thickness measurements. Estimated ganglion cell (GC) counts, calculated from GCIPL measurements, were plotted against 24-2 SITA Faster visual field (VF) thresholds, and regression models were computed with data categorised by diagnosis and VF status. Classification of locations as VF defective or non-defective using GCIPL parameters computed across eccentricity- and hemifield-dependent clusters was assessed by analysing areas under receiver operating characteristic curves (AUROCCs). Sensitivities and specificities were calculated per diagnostic category. RESULTS: Segmented linear regression models between GC counts and VF thresholds demonstrated higher variability in VF defective locations relative to non-defective locations (mean absolute error 6.10-9.93 dB and 1.43-1.91 dB, respectively). AUROCCs from cluster-wide GCIPL parameters were similar across methods centrally (p = 0.06-0.84) but significantly greater peripherally, especially when considering classification of more central locations (p < 0.0001). Across diagnoses, cluster-wide GCIPL parameters demonstrated variable sensitivities and specificities (0.36-0.93 and 0.65-0.98, respectively), with the highest specificities observed across healthy eyes (0.73-0.98). CONCLUSIONS: Quantitative prediction of VF thresholds from widefield OCT is affected by high variability at VF defective locations. Prediction of VF status based on cluster-wide GCIPL parameters from widefield OCT could become useful to aid clinical decision-making in appropriately targeting VF assessments.

Recovery From Homonymous Hemianopia in Hyperglycemia-Induced Occipital Lobe Electroclinical Seizures Following Glycemic Control.

BACKGROUND: Visual changes due to hyperglycemia in diabetes are not uncommon. While blurred vision is a well-established sequela of chronic hyperglycemia, homonymous hemianopia with or without electroclinical seizures is much rarer and can be mistaken for migraine, temporal arteritis, or ischemia of the central nervous system. METHODS: This article analyzed case studies for 3 patients (67M, 68M, 52F) presenting with complex visual phenomena, from 3 to 42 days duration, including pathogenesis, clinical findings, management, and follow-up. RESULTS: Examinations demonstrated dense left homonymous hemianopias in 2 patients and a left inferior homonymous quadrantanopia in one, with no other abnormalities. Patients described vivid, nonstereotyped intermittent hallucinations in the affected fields. Blood glucose levels ranged from 13.5 to 35.0 mmol/L (243-630 mg/dL) without ketosis and HbA1c from 14.6% to 16.8%. Computed tomography of the brain showed no acute intracranial pathology. MRI of the brain either detected no abnormalities or demonstrated changes consistent with seizure activity. Electroencephalogram (EEG) demonstrated seizures over the right occipital region in each patient. EEG seizures coincided with patients' hallucinations, while they remained otherwise conscious. Oral hypoglycemic and antiepileptic medications were commenced with rapid and complete reversal of the seizures and visual field deficits, confirmed by repeat Automated 30-2 and MRI. CONCLUSIONS: Hyperglycemia-induced occipital lobe seizures with visual hallucinations and interictal homonymous visual field defects represent a rare but clinically important diagnosis. This article highlights the importance of prompt recognition and treatment to facilitate recovery.

Ocular microbiome changes in dry eye disease and meibomian gland dysfunction.

The most common and chronic ocular problem of aging is dry eye disease (DED) and the associated condition of meibomian gland dysfunction (MGD). The resident ocular surface bacteria may have a role in maintaining homeostasis and perturbation may contribute to disease development. The aim of this study was to compare the microbiomes of the conjunctiva and eyelid margin in humans with mild and moderate DED and controls using 16 S rRNA gene sequencing. The conjunctiva and lid margin of three cohorts (N = 60; MGD, MGD with lacrimal dysfunction [MGD + LD] and controls) were swabbed bilaterally three times over three months. Microbial communities were analysed by extracting DNA and sequencing the V3-V4 region of the 16 S ribosomal RNA gene using the Illumina MiSeq platform. Sequences were quality filtered, clustered into amplicon sequence variants (ASVs) using UNOISE algorithm and taxonomically classified using a Bayesian Last Common Ancestor (BCLA) algorithm against the GTDB 2207 database. The overall microbial communities of the MGD, MGD + LD and control groups were significantly different from each other (P = 0.001). The MGD and MGD + LD dry eye groups showed greater variability between individuals compared to the control (PERMDISP, P < 0.01). There was decreased richness and diversity in females compared to males for the conjunctiva (P < 0.04) and eyelid margin (P < 0.018). The conjunctiva in the MGD + LD group had more abundant Pseudomonas azotoformans, P. oleovorans and Caballeronia zhejiangensis compared to MGD and control (P < 0.05), while the MGD group had more abundant Corynebacterium macginleyi and C. kroppenstedtii compared to control (P < 0.05). The lid margin in MGD was more abundant in C. macginleyi, C. accolens, and C. simulans compared to the MGD + LD and control (P < 0.05). There were differences in the overall microbial community composition and certain taxa, including increased levels of lipophilic bacteria, on the conjunctiva and eyelid margin in mild to moderate DED/MGD compared to controls. DED/MGD was also associated with a reduced bacterial richness and diversity in females.

Pseudo-hallucinations are for real in some patients with a bipolar disorder.

OBJECTIVE: To provide exemplars of pseudo-hallucinations experienced by six individuals with bipolar disorder, suggest that they may be preferentially overrepresented in those with that condition and argue that their presence does not indicate that the individual is necessarily psychotic. METHOD: Historical definitions of pseudo-hallucinations are overviewed and six profiles are presented considering manifestations in those with a bipolar disorder, their sequencing and response to medication. RESULTS: The six patients initially judged such experiences as true hallucinations and, only over time, did they recognize their falsity. Clinical observation suggests that pseudo-hallucinations may be more common in those with a bipolar disorder and that they can precede, cooccur or follow disorder onset, can manifest during any phase of the condition and that they may or may not respond to medication prescribed for the bipolar disorder. CONCLUSIONS: The exemplars of pseudo-hallucinations overviewed here indicate their richness of expression, their variable time course with illness stages and their variable response to medications prescribed for the bipolar condition.

A comparative analysis of the cephalic microbiome: The ocular, aural, nasal/nasopharyngeal, oral and facial dermal niches.

The human face/head supports a highly diverse population of microorganisms across a diverse range of microhabitats. This biogeographical diversity has given rise to selection pressure resulting in the formation of distinct bacterial communities between sites. This review investigates the similarity and differences of microbiomes across the different biogeographies of the human face and discusses a potential pathway for microbial circulation within individuals and within a population to maintain microbiome niches and diversity.

Comparative analysis of ocular surface tissue microbiome in human, mouse, rabbit, and guinea pig.

Animal models are a critical element of ocular surface research for investigating therapeutic drops, surgical implants, and infection research. This study was a comparative analysis of the microbial communities on conjunctival tissue samples from humans compared to several commonly used laboratory animals (BALB/c mice, New Zealand white rabbits and IMVS colored stock guinea pigs). Microbial communities were analyzed by extracting total DNA from conjunctival tissue and sequencing the 16 S rRNA gene using the Illumina MiSeq platform. Sequences were quality filtered using the UNOISE pipeline in USEARCH and taxonomically classified using GTDB database. Sequences associated with blank extraction and sampling negative controls were removed with the decontam R software package prior to downstream analysis. There was a difference in the diversity measures of richness (P = 0.0124) and Shannon index (P = 0.0002) between humans and rabbits but not between human, mouse and guinea pigs. There was a difference between the human and any animal for bacterial community structure (P = 0.006). There was a higher degree of similarity between the bacterial composition of the human and mouse samples with each dominated by the phyla Proteobacteria and Firmicutes. The use of mouse models may be more appropriate for studies investigating changes to the ocular microbiome due to interventions such as application of antibiotics due to greater similarities in bacterial community structure and composition to humans.

Clinical Trial: Diurnal IOP Fluctuations in Glaucoma Using Latanoprost and Timolol with Self-Tonometry.

SIGNIFICANCE: Assessment of treatment efficacy via comparison with a target IOP is fundamental in monitoring patients with open-angle glaucoma and ocular hypertension. This article highlights that diurnal IOP fluctuations obtained using self-tonometry may more accurately reflect IOP responses to therapy. PURPOSE: This study aimed to investigate fluctuations in diurnal IOP measurements in patients with open-angle glaucoma and ocular hypertension treated with latanoprost 0.005% and timolol 0.25%. METHODS: In this crossover treatment trial, 14 participants performed self-tonometry with iCare HOME 4 times daily for (1) 1 week using latanoprost, (2) 4 weeks using no medications, and (3) 2 weeks using timolol. Daily peak IOPs, IOP fluctuations, and mean IOPs from different treatments were compared on an individual basis. Treatment efficacy between medications was assessed by comparing mean percentage IOP reductions with latanoprost and timolol across participants. In addition, effects of age, years since commencing latanoprost, sex, and diagnosis were investigated, and peak IOP times were compared with assess impacts on diurnal profiles. RESULTS: Between individuals, IOP responses ranged from reductions in peak IOPs, IOP fluctuations, and mean IOPs on both medications to no change in any parameter and medication. IOP fluctuations showed greater mean percentage reductions than did peak and mean IOPs (χ2 = 16.51, P = .002). There were significant associations between years since commencing latanoprost and peak and mean IOP responses on timolol (r = 0.69, P = .007), and sex and relative reductions in IOP fluctuations on both medications (P = .03). There were no differences in peak IOP times between treatment conditions. CONCLUSIONS: Despite variability in IOP responses to latanoprost and timolol, IOP fluctuation with self-tonometry was more consistent in evaluating target IOP, reflecting its importance in ascertaining true IOP response to topical therapies. These findings may impact clinical decision making based on target IOP criteria in patients on topical therapy.

Melanoma incidence in Australian commercial pilots, 2011-2016.

OBJECTIVES: Occupational exposure to cosmic and ultraviolet radiation may increase airline pilots' risk of cutaneous melanoma. Meta-analyses of available data show a higher than average incidence of melanoma in airline pilots, but the most recent systematic review revealed that few contemporary data are available. Moreover, all relevant studies have been conducted in Northern Hemisphere populations. We therefore aimed to examine if Australian commercial pilots have a raised incidence of melanoma compared with the general population. METHODS: We examined all melanoma histologically diagnosed among Australian-licensed commercial pilots in the period 2011-2016 by manually reviewing de-identified data in the medical records system of the Australian Civil Aviation Safety Authority. We estimated age-specific incidence rates and compared these with corresponding population rates using standardised incidence ratios (SIRs) as measures of relative risk. Expected numbers were calculated by multiplying age- and calendar period-specific person-years (PYs) with corresponding rates from the entire Australian population; 95% CI were calculated assuming a Poisson distribution of the observed cases. RESULTS: In this cohort of Australian-licensed commercial pilots observed for 91 370 PYs, 114 developed a melanoma (51 invasive, 63 in situ). More than 50% of melanomas occurred on the trunk, and the predominant subtype was superficial spreading melanoma. The SIR for invasive melanoma was 1.20 (95% CI 0.89 to 1.55) and for melanoma in situ, 1.39 (95% CI 1.08 to 1.78). CONCLUSION: Australian-licensed commercial pilots have a modestly raised risk of in situ melanoma but no elevation of invasive melanoma compared with the general population.

Dry-Eye Disease in Recurrent Pterygium.

PURPOSE: The aim of this paper was to investigate the degree of inflammation and dry-eye disease (DED) in recurrent pterygium. METHODS: Fifty-five patients with a history of pterygium excision were divided into 3 groups - Group 1: no recurrence after the first excision; Group 2: recurrence after the first excision; Group 3: no recurrence after the second excision. Dry-eye symptoms and tear production were elicited for each patient. RESULTS: A high prevalence of DED was observed in patients with primary and recurrent pterygium based on self-reported dry-eye symptoms (63.6%) and an abnormal Schirmer test result (78.1%). There was a statistically significant difference (p = 0.025) in the Schirmer test values between patients with (5.6 mm) and without (11.4 mm) recurrence after surgery for primary pterygium. Patients who were cured after a second excision had an improved Schirmer test value (9.5 mm), although this was not significant. CONCLUSION: Pterygium recurrence is associated with a greater severity of dry eye, possibly by perpetuating ocular surface inflammation in the postoperative period.

Floppy eyelid syndrome "plasty" procedure: Employment of a periosteal transposition flap for surgery of floppy eyelid syndrome.

IMPORTANCE: Floppy eyelid syndrome "plasty" (FESplasty) is a surgical technique that addresses underlying superior tarsal plate and lateral canthal instability in floppy eyelid syndrome (FES) and aims to restore normal anatomical and physiological function to the upper eyelid. BACKGROUND: To describe the use of FESplasty in the surgical management of FES, and to report outcomes in an initial patient cohort. DESIGN: Retrospective study. PARTICIPANTS: Seven patients (nine eyelids) with FES undergoing FESplasty. METHODS: A single surgeon (G.W.) performed all procedures. FESplasty utilizes a periosteal flap based at the inferolateral orbital rim, and applied to the anterior surface of the upper tarsal plate. It is combined with a titrated shortening procedure of the upper eyelid. Patient demographics, comorbidities and ocular symptoms and signs were recorded preoperatively. Pre- and postoperative upper eyelid distractibility were graded and documented. MAIN OUTCOME MEASURES: Postoperative improvement in upper eyelid distractibility and symptomatology, operative complications and FES recurrence. RESULTS: FES symptoms and upper eyelid laxity improved at last follow-up (average 24 weeks) in all patients, with no FES recurrences after a maximum follow-up of 36 weeks. One patient, in whom FESplasty exacerbated his pre-existing aponeurotic ptosis, required definitive ptosis surgery subsequently. There was one case of postoperative wound infection. Obstructive sleep apnoea was present in four of the seven patients. The remaining three patients were awaiting assessment. CONCLUSIONS AND RELEVANCE: FESplasty is likely to confer long-term effective stabilization of the lateral canthal tendon, lateral commissure and superior tarsal plate. Anatomical and functional results appeared to have been successfully achieved.

Repurposing blue laser autofluorescence to measure ocular sun exposure.

IMPORTANCE: Excessive ocular sun exposure is linked to various eye pathologies. Conjunctival ultraviolet autofluorescence (CUVAF) is a method of detecting sun-related conjunctival damage; however, the custom-built camera system required is not readily available. BACKGROUND: We investigated whether blue laser autofluorescence (BAF) on a commonly used confocal scanning laser ophthalmoscope (cSLO) can be utilized to measure CUVAF area. DESIGN: Cross-sectional evaluation of a diagnostic technology at a medical research institute. PARTICIPANTS: Sixty-four participants recruited from three on-going observational eye studies in Western Australia. METHODS: All participants had four images, two of each eye, captured using the CUVAF camera and BAF on the same day. Participants with pterygium or poor quality images were excluded from the analysis. Two graders measured CUVAF area in each image twice. CUVAF area measured by BAF was then compared to measurements determined with the conventional camera system. MAIN OUTCOME MEASURES: CUVAF area. RESULTS: After exclusions, 50 participants' images were analysed. Intra- and inter-observer repeatability were similar between the two systems. When comparing CUVAF area measured by BAF to the camera measurement, grader 1 had a mean difference of +1.00 mm2 , with 95% limits of agreement -5.75 to 7.77 mm2 . Grader 2 had a mean difference of +0.21mm2 , with 95% limits of agreement -7.22 to 7.64 mm2 . CONCLUSIONS AND RELEVANCE: BAF on a commercially available cSLO is a valid method for measuring CUVAF area. This finding provides broader opportunity for identifying, monitoring and educating patients with sun-exposure-related ocular conditions and for researching the ocular impacts of sun exposure.

Paradigm shifts, peregrinations and pixies in ophthalmology.

Human ingenuity is challenged by defending vision, our highest bandwidth sense. Special challenges are presented by the replacement or repair of highly specialized but scarce tissue within the constraints of transparency, tissue shape and alignment, tissue borders and pressure maintenance. Many, mostly destructive, surgical procedures were developed prior to an understanding of underlying pathophysiology. For a number of conditions, both reconstructive and destructive procedures co-exist, yet there are few guidelines as to the better approach. Because the consequences of these procedures may take many years to surface (consistent with a stem cell role in long-term tissue maintenance), guidance may be provided by the elucidation of underlying principles from these approaches. Illustrative examples from clinical, basic research and biotechnology, particularly relating to pterygium, ocular surface squamous neoplasia, dry-eye syndrome, corneal rehabilitation and replacement, cataract surgery, strabismus surgery and bionic eye research, are described. An unexpected consequence of bionic device development has been an appreciation of the sophistication of tissues being replaced, given the limitations of available biomaterials. Examples of how this has provided insights into ocular disease will be illustrated. Stem cell and biomaterial technologies are starting to impact at a time when cost-effectiveness is under scrutiny. Both efficacy and cost will need to be considered as these interventions are introduced. It appears that the paradigm shift rate is accelerating and there is evidence of this in ophthalmology. Lessons learned from the areas of destructive versus reconstructive surgery and the limitations of development of bionic replacements will be used to illustrate how new procedures and technologies can be developed.

Sharpening the focus on ophthalmology teaching: perceptions of medical students and junior medical officers.

IMPORTANCE: Worldwide, ophthalmology teaching is being reduced or eliminated from medical school curricula. The current state of ophthalmic teaching in Australia is unknown. BACKGROUND: To evaluate the perceptions of junior medical officers (JMOs) and medical students on ophthalmology teaching in Australian medical schools. DESIGN: Survey-based cross-sectional study. PARTICIPANTS: A total of 838 JMOs and medical students from across Australia. METHODS: Fifty-six hospitals and 20 medical schools across Australia were contacted. Hardcopy and online surveys were distributed to participants at consenting institutions, evaluating the characteristics of ophthalmology teaching received during medical school and participant confidence in basic ophthalmological clinical skills and knowledge. Factor analysis was performed on confidence scores. MAIN OUTCOME MEASURES: Likert scale confidence ratings, teaching methods encountered versus preferred. RESULTS: Four hundred and thirty-two (51.6%) surveys were received from JMOs and 406 (48.4%) from medical students. The most common form of teaching received were lectures (71.3% JMOs, 65.5% medical students), while the most preferred type were hospital tutorials (37.7% JMOs, 61.6% medical students). Mean confidence in ophthalmology-specific skills and knowledge topics were not high for medical students (skills: 2.66/5, 95% confidence interval [CI] = 2.55-2.76; knowledge: 2.88/5, 95% CI = 2.80-2.96) and JMOs (skills: 2.52/5, 95% CI = 2.43-2.60; knowledge: 2.84/5, 95% CI = 2.77-2.91). Many participants voiced the need for more ophthalmology teaching, particularly clinically oriented opportunities. CONCLUSIONS AND RELEVANCE: JMOs and medical students do not show high levels of confidence in basic ophthalmological clinical skills and knowledge, and report inadequate emphasis on ophthalmology during medical school.

Pterygium and conjunctival ultraviolet autofluorescence in young Australian adults: the Raine study.

BACKGROUND: Sun exposure is associated with several ophthalmic diseases, including pterygium which may develop in adolescence. This study reports the prevalence of pterygium and its associations in a large cohort of young Australian adults. Conjunctival ultraviolet autofluorescence, a biomarker of ocular sun exposure, has recently been characterized in some Australian populations. DESIGN: Cross-sectional population-based study. PARTICIPANTS: One thousand three hundred forty-four subjects aged 18-22 years in the Western Australian Pregnancy Cohort (Raine) Study. METHODS: Standardized colour and ultraviolet autofluorescence photographs of the nasal and temporal conjunctiva were taken, and assessed for presence of pterygium and area of autofluorescence. Sun exposure and protective factors were assessed by structured questionnaire. MAIN OUTCOME MEASURES: Area of conjunctival ultraviolet autofluorescence in square millimetre (mm(2)) and presence of pterygium. RESULTS: Median total conjunctival autofluorescence was 44.2 mm(2) (interquartile range 20.2-69.8 mm(2)). Median conjunctival autofluorescence was higher in nasal than in temporal quadrants (23.8 mm(2) vs. 18.9 mm(2), P < 0.001), but did not differ according to age or gender. Higher body mass index was associated with lower levels of autofluorescence. Total autofluorescence increased with increasing time spent outdoors. Prevalence of pterygium was 1.2% (95% confidence interval 0.6-1.8%), and was associated with male gender (odds ratio 6.71, P = 0.012). Participants with pterygium had significantly more conjunctival autofluorescence than those without (median 73.4 mm(2) vs. 44.0 mm(2), P = 0.001). CONCLUSIONS: Conjunctival ultraviolet autofluorescence is associated with increased time spent outdoors, and increased prevalence of pterygium. The association of this biomarker with other ophthalmohelioses, including cataract, ocular surface squamous neoplasia and eyelid malignancy, has yet to be determined.

LESCs: Lateralizing Eyelid Sleep Compression Study.

PURPOSE: To study the hypothesis that in normal patients, changes in eyelid elasticity may occur asymmetrically and in relation to the side on which the individual sleeps. DESIGN: Prospective, consecutive, single-center study within a large, tertiary-referral ophthalmology department within a university hospital. METHODS: This prospective study was carried out consecutively on 262 normal patients. The 3 inclusion criteria were 1) age≥55 years, 2) absence of facial nerve palsy, and 3) absence of eyelid trauma or surgery. Immediately before the ocular plastic surgeon assessed the patient, each patient was questioned in a separate consulting room by the attending orthoptist as to his or her customary side of sleeping. After detailed explanation, the "history-masked" ocular plastic surgeon then assessed the patient's upper eyelid laxity, the main outcome measurement. This was performed by asking the seated patient to look down and then gently grasping the upper eyelids close to the eyelid margin, just medial to the lateral commissure. The ocular plastic surgeon, with thumbs pronated, simultaneously distracted both upper eyelids superiorly, laterally, and anteriorly. The measured separation of the upper eyelid from the globe conjunctiva was obtained using calipers. Eyelid laxity grading was designated as grade 1: 0 to 1.9 mm; grade 2: 2.0 to 3.9 mm; grade 3: 4 to 9 mm; and grade 4: floppy. RESULTS: Two hundred sixty-two patients (58% females) who consecutively satisfied the selection criteria were evaluated, of which 70.22% (183/262) patients had significantly greater laxity of the upper eyelid that corresponded to the side on which they customarily slept. An unpaired t test used to compare the eyelid laxity between the sleeping side and nonsleeping side was statistically significant (p<0.001). CONCLUSION: Normal patients demonstrate a correlation between the side on which they historically or customarily sleep and the laxity of their ipsilateral upper eyelid.

Examining the fabric of the eye: Antoni van Leeuwenhoek, the draper and ocular microscopist.

We review Antoni van Leeuwenhoek's (1632 - 1723) microscopic studies of comparative ocular anatomy in humans, mammals, birds, and fish. His contributions in anatomical microscopy to ocular biology has been overshadowed by his prolific work and first observations of protists and bacteria, spermatozoa, red blood cells, and dental plaque. Leeuwenhoek's Delftian optical and artisanal heritage more than compensated for any lack of formal scientific training and, in keeping with his Royal Society ethos, shone light onto the "fabric of the eye" in order to better understand its function, which he had extended with his microscopes. He has provided the earliest known microscopic descriptions of the tear film, eyelids, cornea, aqueous, crystalline lens, vitreous, retina, optic nerve, and photoreceptor--as well as the first descriptions of cataract, vitreous floater,s and corneal pathology. His description of the aquatic mammal Cetacean eye foreshadowed an understanding of the optical complexities of aerial and submarine vision of whales. His observations challenged classical teaching at that time, particularly in relation to the optic nerve.