**1. Introduction**

Glaucoma is an optic neuropathy which causes a characteristic loss of optic nerve fibers. The loss of the nerve fibers leads to an increase of the optic disc cupping with subsequent visual field defects [1]. It is estimated that around 60 million people suffer from open angle and closed angle glaucoma with the majority of the patients being female and 47% living in Asia. Another 6 million people suffer from various forms of secondary glaucoma. The patients blind from glaucoma are around 8 million [2,3]. The glaucoma is the second cause of blindness worldwide following cataract.

The aim of the treatment of the glaucoma is the lowering of the intraocular pressure (IOP) as research shown that the higher the IOP the higher the risk of developing glaucoma [4]. In the developed countries the first treatment option is the use of IOP lowering drops while in the developing world trabeculectomy is the first option. Trabeculectomy was regarded as an excellent option for the initial management of glaucoma before the introduction of the newer antiglaucoma drops [6]. Later research showed that patients on topical medication had better quality of life compared to those who underwent trabeculectomy although trabeculectomy was more efficient in lowering the IOP [7]. The introduction of newer and more potent drops as well as further research that showed the failure of trabeculectomy over time, limited the initial enthusiasm of the surgical approach as the initial management of glaucoma [8,9]. This led to a decrease in the number of trabeculectomies performed every year in the developed countries from mid 1990's [10-14].

© 2013 Kozobolis et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **2. Glaucoma surgery overview**

Surgical techniques of the glaucoma surgery include:


**3. Combined cataract–glaucoma surgery**

The main indications for combined surgery are:

**•** the early treatment of glaucoma in cataract patients

**•** the presence of cataract and medically uncontrolled glaucoma

**•** advanced glaucoma and cataract which is likely to progress soon after an antiglaucoma

Combined Cataract-Glaucoma Surgery http://dx.doi.org/10.5772/54808 475

**•** Decreased risk of one surgical and anaesthetic procedure compared to two different

**•** Decreased incidence of postoperative pressure spikes compared to cataract surgery alone

**•** A complicated cataract surgery may compromise the success of the antiglaucoma procedure The procedure that the surgeon will undertake first largely depends on the level of the IOP and the severity of the glaucomatous damage. It is known that phacoemulsification has a small hypotensive effect [15,16, 17]. Phacoemulsification can be considered first when the there is mild glaucomatous damage which progresses very slowly (as assessed by fundoscopy and standard automated perimetry), the IOP is in the mid twenties and the patient's main concern is poor vision due to cataract. Furthermore cataract extraction can take place first if there is a

Trabeculectomy should be considered first if the glaucomatous damage is extensive and/or the IOP is very high and when the cataract operation is likely to intervene with the success of the glaucoma filtering procedure (e.g.: zonular instability due to pseudoexfoliation). The surgeon should be aware of the fact that phacoemulsification following trabeculectomy has a

The combined procedure should be considered when there is significant cataract in the presence of significant glaucomatous damage in a patient whose cataract operation is likely to be uneventful or when the patient would not like to have two separate procedures done or the

bulky cataractous crystalline lens that is the most likely cause of an elevated IOP.

surgeon feels that it is risky for a particular patient to be taken to theatre twice.

adverse effect on the survival of the antiglaucoma procedure [18]

Indications

Pros

Cons

surgical procedure

**•** Less cost to healthcare services

**•** Lengthy procedure that requires experience

**•** Faster visual rehabilitation

procedures

**•** Less operating time

	- **◦** with valve (Ahmed, Krupin)
	- **◦** without valve (Molteno, Baerveldt)
	- **◦** mini shunt (Ex-PRESS)

The concept of minimally invasive glaucoma surgery (MIGS) has gained a lot of interest in the recent years. The aim of these procedures is to minimize the side affects of the classic trabe‐ culectomy by avoiding the formation of a large filtering bleb. The primary indication for MIGS is early to moderate open-angle glaucoma as they tend not to lower the IOP as much as trabeculectomy. The classification of MIGS can vary according to the surgical technique used, the formation of a filtering bleb and the aqueous dynamics

#### **2.1. Classification of MIGS**

Surgical technique


Bleb formation


Aqueous dynamics


All the above techniques can be combined with simultaneous cataract extraction.
