Outcomes of cataract surgery: implications for the developing world

Economic cost of cataract surgery procedures in an established eye care centre in Southern India

PURPOSE

To estimate the direct and indirect costs of three cataract surgery procedures: extracapsular cataract extraction with intra-ocular lens implantation (ECCE-IOL), phacoemulsification (PHACO) and manual small incision cataract surgery (MSICS) using economic costing principles in a well-established eye care programme (Aravind Eye Hospital) in Tamil Nadu, South India during 2000-01. Previous literature suggests that PHACO and MSICS have similar effectiveness.

METHODS

The average unit cost for each surgical procedure was calculated from the societal perspective using economic costing methods. Total annual provider's direct costs for each input to surgery were calculated and apportioned appropriately to different cataract surgery techniques using a 'micro-costing approach'. The patient's direct and indirect costs for each procedure were calculated by interviewing staff and patients and by using assumptions about prices for relevant cost items such as transportation, food, medicine, spectacles and economic productivity loss.

RESULTS

Average provider's direct costs were highest for PHACO procedures (25.55 US dollars) compared to MSICS (17.03 US dollars) and ECCE-IOL (16.25 US dollars). The difference can be attributed to the cost of equipment and materials. Average direct and indirect patient costs were highest for ECCE-IOL (19.85 US dollars), while the costs for PHACO and MSICS were identical (12.37 US dollars). ECCE-IOL had the highest total costs and MSICS had the lowest total costs from the societal perspective.

CONCLUSIONS

Our results suggest that MSICS may have a lower societal cost than other options. Government and NGO hospitals providing cataract surgeries should invest in regular cost analyses, reviews of the literature on effectiveness, and formal cost-effectiveness analyses in order to plan economically efficient interventions. Considering the small incremental cost for providers (less than 1 US dollar), improved outcomes, and lower patient costs, we also believe that MSICS is an important technique to use in efforts to eliminate cataract blindness in India and this result may be generalised to other developing countries.

The effect of light scattering on multifocal electroretinography

PURPOSE

Unclear ocular media is a very common condition of older eyes characterized by significant light scattering and image degradation. The multifocal electroretinography (MERG) is a useful objective technique to measure retinal activity but its validity in the presence of cloudy ocular media remains unclear. We tested the MERG under controlled light scattering conditions using a liquid crystal diffuser (LCD) that simulated different degrees of image degradation.

METHODS

The MERG were taken from 13 normal young subjects seated behind a LCD set under two conditions: scatter (visual acuity approximately 6/18) and non-scatter (visual acuity approximately6/6). The pupils had been dilated and the eyes were optically corrected for the working distance. The first-order kernel MERG response was analysed. Three subjects underwent MERG measurement with two additional intermediate light scattering levels (i.e. visual acuity approximately 6/9 and 6/12).

RESULTS

The macular MERG response density was reduced (p < 0.001), but the peripheral MERG response densities were increased (p < 0.001) under the scattering condition. A similar trend was also observed with intermediate degrees of light scattering. Comparing the MERG waveforms without light scattering, a new retinal response was identified with a characteristic latency of about 60 ms (P60), but it was diminished in size under the scattering conditions.

CONCLUSIONS

The veiling luminance might have caused the reduction in the macular MERG response and an elevation in the peripheral retina with light scatter. The functional suppression of P60 observed under the influence of light scatter may be related to retinal adaptation. Unclear optical media will affect the interpretation of MERG results.