A 62-year-old man with dense nuclear sclerotic cataract in the right eye presents for preoperative evaluation. He reports difficulty reading and driving. Visual acuity is 6/60 in the right eye. Before cataract surgery and IOL implantation, which investigation is most appropriate to assess the functional potential of the eye and guide IOL power calculation?

Explanation

## Investigation of Choice: Potential Acuity Meter (PAM) / Laser Interferometry ### Clinical Context In patients with dense cataracts, the cataract itself prevents direct visualization of the posterior segment and assessment of macular function. Before committing to surgery and IOL implantation, the surgeon must determine whether the poor vision is due to the cataract alone or whether there is coexisting retinal pathology that would limit visual recovery. ### Why PAM/Laser Interferometry? **Key Point:** PAM and laser interferometry bypass the opaque lens by projecting a fine grating or pinpoint light directly onto the retina, allowing assessment of macular function and prediction of best-corrected visual acuity (BCVA) postoperatively. **High-Yield:** PAM is the gold standard for assessing potential vision in dense cataracts. It predicts final visual outcome with ~90% accuracy and helps identify eyes with poor visual prognosis due to macular disease. **Clinical Pearl:** If PAM shows potential vision of 6/12 or better, cataract surgery is likely to be beneficial. If PAM vision is poor (worse than 6/36), retinal pathology is likely and surgery may not improve vision significantly. ### Role of Other Investigations | Investigation | Purpose | Limitation in Dense Cataract | |---|---|---| | A-scan & keratometry | IOL power calculation | Does not assess retinal function | | OCT of macula | Detailed retinal imaging | Cannot penetrate dense cataract; image quality poor | | FFA | Retinal perfusion assessment | Requires clear media; contraindicated in dense cataract | ### Mnemonic: **PAM before CUT** - **P**otential acuity meter - **A**ssess macular function - **M**ust do before cataract surgery - **C**ataract surgery decision - **U**nderstanding visual prognosis - **T**argeting IOL power **Tip:** Always perform PAM/laser interferometry in dense cataracts before surgery to avoid operating on eyes with poor visual potential due to silent retinal disease.