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. 2005 May;89(5):543-6.
doi: 10.1136/bjo.2004.047662.

A novel index for predicting intraocular pressure reduction following cataract surgery

S A Issa  1 , J Pacheco, U Mahmood, J Nolan, S Beatty
Affiliations

A novel index for predicting intraocular pressure reduction following cataract surgery

S A Issa et al. Br J Ophthalmol. 2005 May.

Abstract

Aim: The results of a study designed to investigate the predictive value of preoperative anterior chamber depth (ACD) and intraocular pressure (IOP) are reported. The relation between these factors and their effect on the reduction in IOP following phacoemulsification cataract surgery was also studied.

Methods: The ACD and IOP were prospectively measured in 103 non-glaucomatous eyes of 103 patients who underwent uneventful phacoemulsification and posterior chamber intraocular lens (PCIOL) implantation. Other data which were recorded included best corrected visual acuity, axial length, lens thickness, and severity of lens opacity.

Results: The ACD increased by a mean (SD) of 1.10 (0.44) mm (p<0.00001) and this increase was significantly and inversely related to preoperative ACD (r(2) = 68%; p<0.01). IOP dropped by a mean of 2.55 (1.78) mm Hg following cataract surgery (p<0.0001), and this reduction was significantly and positively related to preoperative IOP (r(2) = 56%; p<0.01), and significantly and inversely related to preoperative ACD (r(2) = 21%; p<0.01). A novel ratio, the pressure to depth (PD) ratio (preoperative IOP/preoperative ACD), was found to be significantly and positively related to the surgically induced reduction in IOP (r(2) = 73%; p<0.01), and IOP was reduced by > or =4 mm Hg in all patients with a PD ratio >7.

Conclusion: The reduction in IOP following cataract surgery was found to be positively related to preoperative IOP, and inversely related to preoperative ACD. Furthermore, these results indicate that a novel index, the PD ratio, is strongly predictive for IOP reduction following cataract extraction, and may prove useful in surgical decision making.

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Figures

Figure 1
Figure 1
The relation between preoperative and postoperative ACD after cataract surgery. The solid line plotted is the line of equivalence.
Figure 2
Figure 2
The relation between preoperative IOP and IOP reduction after cataract surgery. Note that IOP drop is plotted as a positive value. Random noise of not more than plus or minus 0.1 was superimposed onto both x and y values to ensure that a maximum number of data points were visually represented. IOP, intraocular pressure.
Figure 3
Figure 3
The relation between preoperative ACD and IOP reduction following cataract surgery. Note that IOP drop is plotted as a positive value. Random noise of not more than plus or minus 0.1 was superimposed onto IOP drop values to ensure that a maximum number of data points were visually represented. ACD, anterior chamber depth; IOP, intraocular pressure.
Figure 4
Figure 4
The relation between PD ratio and IOP reduction following cataract surgery. Note that IOP drop is plotted as a positive value. Random noise of not more than plus or minus 0.1 was superimposed onto IOP drop values to ensure that a maximum number of data points were visually represented. IOP, intraocular pressure; PD ratio, intraocular pressure to anterior chamber depth ratio.
See this image and copyright information in PMC

Comment in

  • Cataract surgery and IOP.
    Fraser S, Phelan PS. Fraser S, et al. Br J Ophthalmol. 2005 Sep;89(9):1228. doi: 10.1136/bjo.2005.073874. Br J Ophthalmol. 2005. PMID: 16113394 Free PMC article. No abstract available.

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