Recommendations for intraocular pressure measurement one hour after laser peripheral iridotomy: Review of the literature

PURPOSE

To determine the need to measure intraocular pressure one hour after laser peripheral iridotomy in patients with narrow angles, to determine the significance of the immediate IOP spike after LPI, and to assess risk factors associated with these.

METHODS

A review of the literature on IOP measurements after LPI was conducted using the PubMed databases in January 2020.

RESULTS

The proportion of treated eyes with an IOP spike one hour after treatment was between 6 and 9.8% depending on the study. Fewer than 1% of the eyes had an immediate post-treatment IOP of 30mmHg or more. Risk factors associated with IOP spikes include hyphema, pigment dispersion, and high pretreatment IOP. Patients of Asian descent, who possess thick irides, or any patient having thick irides, also exhibited increased risk of IOP spikes.

CONCLUSIONS

The majority of the studies that have evaluated this complication were conducted in an Asian population, which affects the generalisability of these results to a wider population, considering anatomical differences. Although it is not uncommon to observe IOP spikes following LPI, the majority will not experience an increase of 10mmHg from baseline or a post-LPI IOP of 30mmHg or more. Even though it has been recommended to measure the IOP of all patients one hour after an LPI in order to avoid missing a spike, we suggest measuring IOP one hour after an LPI in patients who possess at least one risk factor or if there is any preexisting damage to the optic nerve.

Role of presensitization and donor-recipient crossmatching in corneal graft outcome

PURPOSE

A positive donor-recipient crossmatch (CM) due to preexisting recipient lymphocytotoxic antibodies is known to be an important factor in allograft failure in the majority of organ transplantations. However, the effect of positive CM on corneal graft outcome is less known.

METHOD

Between 1982 and 1994, CM was performed by the microlymphocytotoxicity method using donor lymphocytes and recipient pretransplant serum in 759 consecutive corneal transplantations (maximal follow-up, 36 months). Patients were evaluated regarding the type of allospecificity of antibodies involved and their role on corneal graft outcome (rejection and failure).

RESULTS

A positive CM was found in 61 patients (8%) and a negative CM in 698 patients (92%). The positive and negative CM groups had similar graft rejection rates at 36 months. Patients with a positive CM due to antibodies directed against donor human leukocyte antigen (HLA) (as defined on the basis of private and public or CREG HLA allele specificities) did not have an increased risk of rejection. However, patients with positive CM and presensitization (previous graft or rejection history) had a statistically significant increase in risk of corneal endothelial rejection.

CONCLUSION

This study shows that donor-recipient CM could be a useful procedure for the selection of recipients for corneal transplantation in patients presensitized by anterior graft or previous corneal rejection.

Role of ABO and Lewis blood group antigens in donor-recipient compatibility of corneal transplantation rejection

PURPOSE

There are conflicting results regarding the role of human leukocyte antigen (HLA) matching and ABO compatibility in corneal graft rejection for low- and high-risk patients. Lewis blood group antigens could be an important histocompatibility system. Beneficial effects of Lewis antigens matching have been reported in renal transplantation, but its effect is still unknown in corneal allografting.

METHODS

Between 1987 and 1993, ABO, Lewis and HLA phenotypes were determined in 697 consecutive grafts of corneal transplantations. The effect of Lewis matching on corneal endothelial rejection was evaluated over a 3-year period. Data analysis was done by plotting survival curves with the Kaplan-Meier method for survivorship data and performing statistical analysis with the log-rank test (Mantel-Haenszel test) for curve comparison.

RESULTS

In vascularized recipients, the ABO, Lewis, and HLA systems did not influence the graft outcome. However, for the unvascularized recipients, the endothelial 3-year rejection rate was significantly lower for both Lewis compatible patients (84% vs. 68%; log rank = 0.03) and HLA compatible patients (86% vs 72%; log rank = 0.001), but not for the ABO-matched patients (82% vs. 79%; log rank = 0.56).

CONCLUSIONS

The authors' study suggests that Lewis antigens and HLA matching could positively influence corneal graft survival for the unvascularized recipients, but it did not seem to have any effect in vascularized recipients.