A Preventive Intervention For Rising Intraocular Pressure: Development of the Molloy/BAA Observation Scale

Date of Completion

January 2010


Health Sciences, Ophthalmology|Health Sciences, General|Health Sciences, Nursing




Background There is increasing interest in monitoring intraocular pressure (IOP) during surgery in steep Trendelenburg (ST) position with cited incidents of postoperative visual loss (POVL). Successful interventions to decrease rising IOP intraoperatively have also been described. A review of 17 POVL patients showed findings of eyelid edema, corneal edema and ecchymosis. Measuring IOP intraoperatively requires costly tonometers and credentialed personnel. The aim of this study was to link gold standard IOP tonometry measurements to an observation scale enabling caregivers to determine when to institute neuroprotective measures to optimize ocular perfusion. The Molloy/BAA Observation Scale (MBOS) was developed and tested to provide anesthesia caregivers with a valid, reliable, brief and easy to use observation scale correlated to increases in IOP. ^ Methods The study design was a prospective repeated measure correlation regression model. A total of 111 patients undergoing ST position surgery were enrolled. The MBOS includes observations of presence of eyelid edema, corneal edema/chemosis, ecchymosis and baseline IOP determining the probability of when a > 40 mmHg IOP (critical threshold) will be reached. Measures were recorded at the start of surgery and at 30 minute intervals throughout procedure. Multivariate logistic regression analysis using the generalized estimating equations (GEE) method was employed. ^ Results The MBOS parameters significantly correlated to increasing IOP. The components of the final model found as significant predictors of > 40 mmHg IOP were determined to be presence of chemosis and baseline IOP. The receiver operating characteristic curve area under the curve score was 0.86 (SE 0.03). Presence of chemosis alone area under the receiver operator characteristic curve was 0.79 (SE 0.03). A probability scale via estimated log odds ratios determined likelihood of reaching > 40 mmHg with baseline IOP values and presence or no presence of chemosis.^ Conclusion Observed findings of chemosis and baseline IOP can provide the anesthesia caregiver with a probability scale of when critical threshold > 40 mmHg may be reached. Caregivers can observe findings and utilize MBOS to assess the need and timing for interventions to normalize IOP.^