Ophthalmic viewing lenses offer indirect cost savings

When I first qualified as an optometrist some 25 years ago, viewing the retina by slit-lamp biomicroscopy was very much considered an add-on specialist technique. This is certainly no longer the case and the many advantages of indirect fundus viewing with a supplementary lens (Table 1) make slit-lamp BIO the first choice ophthalmoscopy technique for many. I have just completed another round of assessments for the College and would say that a majority of pre-registration optometrists now use slit-lamp BIO as their main method of fundus viewing.

I currently have three non-contact fundus viewing lenses, all glass and from Volk. I use a higher-power wide-field lens for general retinal viewing and find this especially useful for patients with extensive lesions such as widespread diabetic retinopathy. For a more magnified view of the disc or a suspect macula I use a Super 66 lens. A third 20DS lens is for the very occasional ventures with the headset BIO, although this is mainly in teaching these days. The important thing I realised some time ago was that having more than one lens was important (Figure 1). If I used the wider field lens to view a smaller lesion or area and increased the magnification on the slit lamp, the image gained was of much poorer resolution than if I used a lower power, higher magnification lens with the slit lamp on constant magnification. Furthermore, a lower power lens allows me to align the vertical slit of the lamp with the in-focus disc and use the slit length to indicate the height of the disc. This is particularly useful in assessing the potential for glaucomatous change.