The traditional approach to office evaluation of patients being considered for cataract surgery begins with obtaining a history of significant visual symptoms followed by visual function testing and refraction, IOP measurement, slit lamp examination – hopefully including 90 D lens examination of the macula and optic nerve – and, finally, dilated pupil retinal examination with the indirect ophthalmoscope. If the visual function, visual complaints and slit lamp examination verify the need for cataract surgery; the next step is an array of tests to determine lens implant power, axis, and other parameters. In my view, OCT should also be performed in all patients.
Because of the explosive progress in development of advanced technologies to determine corneal optics and axial length, as well as multiple advanced IOL calculation algorithms, refractive surprises are becoming much less common. “Visual surprise” is a term I have coined to describe the combination of a near perfect refractive outcome with unanticipated vision less than perfect. There are many factors that result in the visual surprise scenario. Although cataract interference with macular visualization is obviously a prime factor, indirect ophthalmoscopy has insufficient resolution to evaluate the macula (but it is essential to detect retinal detachment, retinal holes/breaks, lattice degeneration and other peripheral retinal pathologies); another factor is retinal examination that is performed by someone with inadequate training or experience. Many macular disease processes – such as early wet age-related macular degeneration (AMD), vitreomacular traction syndrome, vitreomacular schisis, moderate diabetic macular edema, mild-to-moderate epimacular membranes, and small macular holes – are all very difficult or impossible to see using a slit lamp and a 90 D or fundus contact lens, and use of widefield imaging technology as the sole method of retinal evaluation is simply not good medical practice. Central serous chorioretinopathy (CSR) is often virtually invisible, but it is becoming more common because of widespread steroid use (nasal inhalers for sinus disease, asthma inhalers, pain management injections, topical steroids for dermatologic conditions, and oral steroids for pulmonary diseases and collagen vascular diseases are all taken by more patients than you might expect).
Fortunately, OCT technology allows us to detect and evaluate all the disease processes listed above. It is fast, easily performed by technicians, requires no dye injection, and has no unit cost other than labor. I feel strongly that OCT has become an essential part of the pre-surgical examination of all cataract patients, not just patients that will be receiving premium IOLs. OCT imaging has also become essential for the evaluation of nerve fiber loss from glaucoma and can be performed on the same device used for macular evaluation; the prevalence of both glaucoma and macular disease makes this a valid approach. How best to use this essential tool? Pseudo-color, 3D rendering and thickness maps obscure pathology and create artifacts, and so should not be used. Instead, all black and white gray scale slices should be viewed by the ophthalmologist – easily and rapidly done using the mouse scroll wheel. The images should be viewed using the native OCT device software, and it is a bad idea for a technician or photographer to pick an image to import into the electronic medical record. Fundus auto-fluorescence is possible with several modern OCT instruments and is a highly sensitive tool when it comes to evaluating geographic atrophy in dry AMD patients, as well as retinal pigment epithelium changes from CSR. In summary, performing OCT is essential in the evaluation of all patients before cataract surgery; it prevents visual surprises and leads to expeditious and appropriate management of macular diseases.
