Profile of glaucoma cases seen at a tertiary referral hospital

GLAUCOMA, the leading cause of irreversible
blindness, affects nearly 67 million people worldwide, with
almost equal number of open angle and angle closure.
Another 6 million have secondary glaucoma, bringing the
total to 73 million, excluding childhood cases.
1
Population-based studies in Singapore, Thailand, and
Malaysia reported prevalence of glaucoma at 3.2%, 3.8%
and 0.7% respectively.
2-4
These studies indicated that
primary open-angle glaucoma (POAG) was more common
than primary angle-closure glaucoma (PACG) with ratios
of 3.2:1, 1.6:1, and 1.5:1 respectively.
5
In the Philippines,
angle-closure glaucoma may be the predominant type
based on hospital surveys.
5
The Third National Survey on Blindness conducted in
2002 ranked glaucoma as the third most common cause
of bilateral blindness and the fifth most common cause
of low vision in the Philippines.
6
The survey projected that
a total of 71,821 Filipinos have glaucoma, 18,620 of whom
are bilaterally blind. The extrapolation was based solely
on previously diagnosed cases or an increase in intraocular
pressure (IOP) as measured by Schiotz tonometry during
the sampling period. It is, therefore, likely that the effects
of the disease are underestimated.
Population-based studies are desirable in determining
the prevalence and incidence of a disease; oftentimes,
however, they are difficult, costly, and time consuming to
conduct. Tertiary referral centers offer a diverse population of patients and can provide a general overview of
certain disease profiles. This study determined the demographic and clinical profile—predominant types of
glaucoma, pattern of distribution, predominant findings,
and treatment given—of glaucoma patients seen at the
Glaucoma Clinic of the University of the PhilippinesPhilippine General Hospital (UP-PGH) from 2000 to 2002.

METHODOLOGY
Clinical charts of patients were reviewed. A standardized
data-collection form was devised. Patient information such
as age, gender, chief complaint, duration of symptoms,
ocular findings, and initial treatment given were entered
into Microsoft Excel (Microsoft Corporation, Redmond,
WA, USA).
Visual acuity (VA) was obtained with a Snellen chart
and converted to the decimal system. IOPs were obtained
with either the Goldman or Perkins applanation
tonometer. Estimating the vertical cup-disc ratio (CDR)
was done either with the Goldman lens, 78D or 90D
aspheric lenses at the slitlamp, or direct ophthalmoscope.
Gonioscopy was performed using either the 3-mirror
Goldman lens or the Zeiss 4-mirror lens. Visual fields were
tested with the Humphrey Field Analyzer (Humphrey
Corp, San Leandro, CA USA) using the threshold 24-2 or
30-2 test strategy. The specific type of glaucoma was
determined based on the clinical presentation, opticnerve-head findings, visual-field changes, IOP, and
gonioscopic findings. The eye with the worse visual acuity
and/or visual-field defect was included in the analyses.
Initial management, defined as the therapy instituted
within the first two weeks of consultation at the glaucoma
clinic, was classified as any of the following: (1) observation
or no intervention, (2) medical therapy only, (3) laser, or
(4) surgery. Medical management consisted of IOPlowering agents such as beta-blockers, alpha-agonists,
topical and systemic carbonic anhydrase inhibitors (CAI),
prostaglandin analogs, glycerol, and intravenous mannitol.
Laser procedures included laser iridotomy (LI), laser iridoplasty, argon laser trabeculoplasty (ALT), and diode cyclophotocoagulation (CPC). Surgical procedures performed
were trabeculectomy, combined cataract extraction with
filtration surgery, cataract surgery alone, cyclocryotherapy
(CCT), goniotomy, trabeculotomy, pars plana vitrectomy,
and glaucoma-drainage-device (GDD) implantation.
Descriptive statistics were employed and the data
compared.

RESULTS
A total of 866 charts were reviewed. Thirty patients had
no glaucoma and were excluded; 836 patients were
subsequently included in the study.
The demographic characteristics of the study population are summarized in Table 1. The mean age was 55
years and there were more females. The most common
chief complaints on consultation were blurring of vision
and eye pain. The mean best-corrected visual acuity
(BCVA) was 20/60, mean IOP was 27.2 mm Hg, and mean
vertical CDR was 0.7.
Table 2 shows the different types of glaucoma in the
study population. The top three glaucoma conditions were
PACG (29.5%), POAG (14.4%), and lens-induced
glaucoma (8.0%). Glaucoma suspects (GS), defined as
increased CD ratio of 0.6 or greater with normal visual
fields were also frequently seen (20.3%).
In those with PACG, 17.4% were acute or subacute and
82.6% were chronic. Thirty-four percent had no light
perception (NLP). In those with POAG, 18.3% were
classified as normal tension and 6.7% juvenile. Majorityv of the lens-induced glaucoma were either phacomorphic
(74.6%) or phacolytic (17.9%).
The most common initial treatment modalities were
observation, medical therapy only, and laser. Topical betablockers and systemic CAI were the most commonly
prescribed medication, while LI was the most frequently
performed laser procedure. Trabeculectomy, combined
lens extraction and filtration surgery, and lens extraction
alone were the most common surgical procedures
performed (Table 3).
PACG, POAG, and secondary glaucoma are compared
in Table 4. Those with secondary glaucoma were younger
and had poorer visual acuity. Compared to POAG, those
with PACG were older, had poorer visual acuity, higher
IOP, and a higher percentage of NLP vision (Table 5).
More than half of PACG (56.2%) underwent some form
of glaucoma procedure as the initial treatment and 36.7%
had glaucoma surgery. Majority of POAG received medical
treatment only.

DISCUSSION
The most common types of glaucoma seen in a tertiary
government hospital were PACG, POAG, and lens-induced
glaucoma. Many patients consulted late in the course of
the disease and had NLP, a high percentage of which was
seen in PACG and secondary glaucoma (Table 4). IOP
was also higher in these groups associated with poorer
vision, indicating the severity of glaucomatous optic
neuropathy (GON). A comparison of POAG and PACG
(Table 5) showed that untreated PACG resulted in more
loss of vision and is a more devastating disease that
frequently requires filtration surgery (Table 6). This is
also corroborated by other studies,
7-8
emphasizing the
need for early diagnosis and treatment. PACG causes more
destruction to the eye in the form of advanced GON, loss
of central vision, and uncontrolled IOP due to the closure
of the drainage angle, either acutely or chronically, that
eventually becomes unresponsive to medical or laser
treatment. In contrast, POAG is associated with a more
gradual increase in IOP that is generally responsive to
medical therapy and causes vision loss much later if left
untreated. Lens-induced glaucoma, specifically the
phacomorphic type, is associated with a rapid increase in
IOP resulting from angle closure due to a pupillary block
that occurs as a result of increased contact between the
lens and the iris. If the condition is not treated
immediately, total loss of vision and permanent closure
of the angle can result.
A survey done 20 years earlier at the same institution
revealed that PACG and POAG were the most common
types of glaucoma, accounting for 35% and 31% of the
total cases respectively.
9
In both surveys, PACG was more
common than POAG. Caution, however, should be
exercised in extrapolating that PACG is the predominant
type of glaucoma in the Philippines as patients that come
to UP-PGH are those who tend to seek consultation late
(> 6 weeks in 83.2%) because of economic reasons.
Moreover, they tend to seek consultation only when the
disease is symptomatic, such as in the presence of acute
pain (14.5%) or blurring of vision (67.5%). Both symptoms
were the most common complaints on consultation
(82%), indicating that the study population was biased
toward the more severe nature of the disease. As in other
studies,
10, 11, 12
this study showed that those with PACG were
likely to be older, female, and have higher IOP and poorer
visual acuity with a larger percentage of NLP. POAG is
more common among males and generally respond well
to medical therapy (65%), in contrast to PACG where the
majority had either laser (19.5%) or surgical treatment
(36.7%). A large percentage (27%) of PACG in this study
were initially managed by observation, reflecting the high
percentage of NLP vision in this group where treatment
is no longer cost-effective.
Lens-induced glaucoma was the third most common
condition causing elevated IOP and GON in this study.
Due to the delay in treatment of the enlarged cataractous
lens, resultant complications such as glaucoma developed,
indicating that the type of patients seeking care at
government referral hospitals tend to seek medical
treatment late and were likely to have more advanced
disease and complications.

A high percentage of glaucoma suspects was also seen
in this study. An overestimation is possible as the diagnosis
of the condition was based on an enlarged cup-disc ratio
without taking into consideration the size of the disc. One
major limitation of chart reviews is the variability
encountered in estimating the size of the cup by different
clinicians. Obtaining standard stereoscopic optic-disc
photos and evaluating them by trained experts (glaucoma
specialists) would be more appropriate and would reduce
the prevalence of glaucoma suspects in this population.
In summary, PACG and POAG remain the two most
common types of glaucoma seen among patients seeking
treatment at the UP-PGH, a government referral hospital.
Because of the select population that this institution serves,
any conclusion regarding the two types of glaucoma in
this country cannot be drawn. A population-based study
is, therefore, needed to establish the true incidence and
prevalence of glaucoma in the Philippines.