Design of an intraocular pressure curve protocol for use in dogs

Objectives To establish an intraocular pressure curve protocol that is safe for corneal health and detects harmful elevations of intraocular pressure outside normal clinic hours. To determine inter‐user variability and if repeated measurements affect intraocular pressures. Materials and Methods Intraocular pressures were measured in dogs with glaucoma using three protocols: Protocol 1 used applanation tonometry every 2 hours over a 24‐hour period; Protocols 2 and 3 used applanation or rebound tonometry, respectively, and measured intraocular pressures every 3 hours over a 30‐hour period. A total of 60 additional intraocular pressure curves from dogs with glaucoma and 20 from healthy dogs were then analysed for inter‐user variability. Results A total of 128 intraocular pressure curves were determined in 30 dogs. Protocol 1 resulted in one ulcer in five pressure curves, Protocol 2 in one ulcer in 62 pressure curves and Protocol 3 in no ulcers in 61 pressure curves. Elevated intraocular pressures were detected on 61 occasions, of which 26 developed outside normal clinic hours. A total of 61 additional intraocular pressure curves revealed that repeated measurements had no effect on intraocular pressure. Clinical Significance Protocol 3, using rebound tonometry every 3 hours for 30 hours is safe corneal health and identified elevated intraocular pressures outside normal clinic hours in 12 of 30 (40%) patients that single intraocular pressure measurement during consultation hours would not have identified. Intraocular pressure curves may be recommended for clinical practice and glaucoma studies.