Chapter 5: Future Research

	As discussed in the conclusions, the literature addressing management of coexistent cataract and glaucoma has important limitations.  We will first address those limitations general to the entire literature and then those that are specific to individual questions.

	As mentioned previously, although glaucoma is characterized by structural and functional damage to the optic nerve, the extant literature concentrates on intraocular pressure (IOP).  It will be important for future studies to assess the effect of surgery upon the appearance of the optic nerve, visual field, patient preferences and quality of life in addition to IOP.  Because of the chronic and slowly progressive nature of glaucoma, these parameters need to be evaluated in long-term (5 years or greater) studies.

	Future studies should pay more attention to the quantification of cataract and its effect upon vision.  The existing literature is generally lacking in any objective description of the crystalline lens, whether clear or cataractous.  Quantifying lens opacity and assessing its effect upon vision and vision related quality of life should be a priority for future studies.  Standardized grading systems for cataract (already in use) should be employed.

	Although the literature represented populations in North America, Europe, and Asia, few of the reports included significant numbers of African-Americans.  This population has a high prevalence of glaucoma, and may respond differently to glaucoma surgery.  Future researchers must strive to include more African-Americans in their studies.

	As described in Chapter 4: Conclusions, assessment of the evidence was limited by its quality, particularly in the areas of  bias and confounding.  Specifically, a lack of comparability of study groups and an absence of masking of observers greatly compromised the validity of many studies.  Future studies would be well advised to pay particular attention to striving for comparability of study groups and statistical adjustment for baseline differences, as well as implementing more objective measures for assessing outcomes.  A large number of ophthalmology journals are signatories to the CONSORT statement, which outlines standardized criteria for reporting the results of randomized clinical trials.114  Adherence to these standards is one way that trials reporting may be improved.

	The following specific questions point to potential areas for future research, both because of their importance and the fact that questions remain unresolved by the extant literature:	

•	Does trabeculectomy alone lower IOP more than phacoemulsification plus trabeculectomy?

•	Does phacoemulsification harm functioning filtering blebs? 

•	Does phacoemulsification reliably result in lower IOP on the first day after surgery?  If so, then it might not be necessary to perform combined surgery. 

•	Does a two-stage procedure provide lower IOP than a combined procedure? 

•	What is the role of mitomycin-C in combined procedures and how should it be administered?

•	Is the finding of decreased posterior capsular opacification with the use of mitomycin-C reproducible?

•	Can better glaucoma procedures be developed to be used in conjunction with cataract surgery?

•	What are the risk factors for cataract development and progression following glaucoma surgery?