On the invention of the ophthalmoscope

The author offers an English translation of three passages of Purkinje'sCommentatio de examine physiologico organi visus (1823). He shows that Purkinje made three inventions: (1) by using a transparent mirror, (2) by anticipating Maxwellian illumination, and (3) by providing the first recorded ophthalmic examination of animal and human eyes.     

A new technique of indirect ophthalmoscopy for the eye plastic surgeon

The coaxial fiberoptic headlight used by the lacrimal and orbital surgeon is an excellent light source for visualization of the retina. When employed in conjunction with a condensing lens, an inverted stereoscopic aerial image is produced. The eye plastic surgeon might therefore routinely examine the dilated patient in conjunction with lacrimal or orbital surgery.     

Dynamic distance direct ophthalmoscopy, a novel technique to assess accommodation in children

Aim:

To describe and compare dynamic distance direct ophthalmoscopy (DDDO) with dynamic retinoscopy (DR) in assessment of accommodation in children.

Materials and Methods:

This prospective observational study had four components. Component 1: to understand the characteristic digital images of DDDO. Component 2: to compare DDDO with DR for detection of accommodative defects in children (1–16 years). Component 3: to compare DDDO with DR for the detection of completeness of pharmacologically induced cycloplegia in children (5–16 years) and Component 4: to assess which one of the two techniques was more sensitive to detect onset of cycloplegia after instillation of 1% cyclopentolate eye drops.

Results:

Component 1: image analysis of DDDO on two subjects (7 years and 35 years) demonstrated superior pupillary crescent that progressively disappeared with increasing accommodation. Concurrently an inferior crescent appeared that became bigger in size with increasing accommodation. Component 2: the prevalence of defects in accommodation was 3.3% (33/1000 children). Three had unilateral accommodation failure. Sensitivity of DDDO was 94%, specificity 100%, positive predictive value 100%, negative predictive value 99%, and clinical agreement (kappa) 0.97. Component 3: in the detection of completeness of pharmacologically induced cycloplegia (n=30), the sensitivity of DDDO was 94%, specificity 96%, positive predictive value 97%, negative predictive value 93% and kappa 0.9. DR had two false positives. DDDO had one false negative. Component 4: DDDO detected onset of pharmacologically induced cycloplegia 5 min earlier than DR (n=5).

Conclusion:

DDDO is a novel, simple, clinical and reliable method to assess accommodation in young children. This test can assess the accommodative response of both eyes simultaneously.     

The optics of comparative ophthalmoscopy

One factor peculiar to the practice of comparative ophthalmoscopy is the very large variation in ocular size of the animals examined, a factor which is ignored in current textbook treatments of the subject. We have computed values of lateral magnification, axial magnification, angular field of view and linear field of view for 19 species of terrestrial vertebrates. The dimensional value of a 1 diopter change in direct ophthalmoscopic focus was also determined. The anterior focal length of the eye in air and the vitreal refractive index were the intrinsic optical parameters of the animal's eye necessary for these calculations. Where these values were not available from the literature, the vitreal refractive index was assumed to be 1.336 and the anterior focal length was estimated as two-thirds of the axial length using a regression equation we derived from data in the literature. The angular field of view in ophthalmoscopy was shown to be invariant in the emmetropic eye and equal to the angular subtense of the ophthalmoscopic beam. The lateral field of view and retinal depth corresponding to a 1 diopter change in direct ophthalmoscopic focus varied directly with the anterior focal length of the eye. The remaining parameters of lateral and axial magnification varied inversely with the anterior focal length of the animal's eyes. These findings provide a basis for evaluating the relative size and significance of ophthalmoscopically viewed features in terrestrial vertebrate eyes.     

Sesquicentennial of the ophthalmoscope

The year 2000 coincides with the 150th anniversary of the invention of the ophthalmoscope. In 1850, Hermann von Helmholtz (1821-1894) inaugurated the modern era in ophthalmology with his magnificent instrument, which has done more to revolutionize the development of ophthalmology than any other invention or discovery. Before Helmholtz's invention, it was not possible to visualize the posterior pole of the eye in a living subject. The ophthalmoscope permitted the clinical correlation of signs and symptoms with findings in the retina, vitreous, and optic nerve. The ophthalmoscope became the model for all forms of endoscopy that followed. It is often compared in importance with 2 earlier inventions, the telescope (17th century) and the stethoscope (early 19th century). All of these instruments made dramatic new information available to the human mind.     

The Utrecht ophthalmic hospital and the development of the ophthalmoscope

The first useful table model ophthalmoscope was designed by Donders and the instrumentmaker Epkens. With the use of this instrument Donders' pupil Van Trigt made the first drawings of the normal and pathological fundus of the eye. His contribution was of great importance for the early diffusion of knowledge of the fundus of the eye.     

Objectives of teaching direct ophthalmoscopy to medical students

Purpose: To propose the objectives of undergraduate training in direct ophthalmoscopy (DO). Method: Narrative review of the literature on (i) opinions about the expected proficiency from students in DO, and (ii) estimates of its diagnostic value. Results: (i) Authorities disagree on the proficiency in DO that they expect from students. Textbooks of physical diagnosis differ in their coverage of DO. Surveys have indicated that US physicians expect students to be able to detect optic nerve head abnormalities. The Association of American Medical Colleges expects students to perform ophthalmoscopic examination and describe observations. The International Council of Ophthalmology expects students to recognize also diabetic and hypertensive retinopathies. The Association of University Professors in Ophthalmology requires that students recognize papilloedema, cholesterol emboli, glaucomatous cupping and macular degeneration. (ii) There is evidence that DO, even by ophthalmologists, is inadequate for screening for glaucoma, diabetic and hypertensive retinopathies. Two studies have suggested a limited value of DO in detecting clinical emergencies. Conclusions: The evidence that DO, even by ophthalmologists, is sub‐optimal in detecting common abnormalities challenges existing the notions of training medical students. On pending the results of additional studies of the value of DO in detecting emergencies, we suggest that undergraduate teaching of DO should impart the following: (i) an ability to identify the red fundus reflex and optic disc; (ii) an ability to recognize signs of clinical emergencies in patients, mannequins or fundus photographs; and (iii) knowledge about, but not an ability to detect, other retinopathies.     

On the evolution of binocular ophthalmoscopy

The need for stereopsis arose soon after the discovery of the ophthalmoscope, not least because the glaucomatous cup was mistaken for a swelling. At that time, Brewster's popular stereoscope was already in use, and its theory and method were then applied to ophthalmoscopy by Giraud-Teulon. His was the first binocular instrument, subsequently much improved by Zachariah Laurence. Binocular indirect ophthalmoscopy was abandoned toward the end of the 19th century in favor of direct monocular ophthalmoscopy, until it was revived in the 1950s by Schepens.     

The invention and early manufacture of bifocals

Benjamin Franklin, who died 200 years ago, is generally credited with the invention of bifocals. However, serious historians have from time to time produced evidence to suggest that others may have preceded him in the invention. This historical article includes correspondence from George Whatley, a London philanthropist, and John Fenno, editor of The Gazette of the United States, which convincingly documents that Franklin invented bifocals, perhaps 50 years earlier than has been generally thought. Appendices detail the many difficulties encountered in the early manufacture of bifocals.