Early elevation of intraocular pressure following diabetic vitrectomy

1
Early elevation of intraocular pressure following
diabetic vitrectomy

• Authors
• Archna Pruthil, MD1
• Yog Raj Sharma, MD1
• Raj Vardhan Azad, MD1, FRCSEd.
• Atul Kumar, MD1
• Rashim Mannan, MD1
• 1. Dr Rajendra Prasad Centre for Ophthalmic
  Sciences, All India Institute of Medical
  Sciences, New Delhi-110029, India
• Place of study Vitreo-Retina Services, Dr
  Rajendra Prasad Centre for Ophthalmic Sciences,
  All India Institute of Medical Sciences, New
  Delhi-110029, India.

2
ABSTRACT

• PURPOSE To study the incidence and risk factors
  for elevated intraocular pressure (IOP) following
  pars plana vitrectomy (PPV) for proliferative
  diabetic retinopathy (PDR).
• METHODS The IOP and best corrected visual acuity
  (BCVA) for 73 cases of PDR that underwent PPV
  were recorded at day 1, week 1, month 1, 3 and 6.
  Risk factors for early IOP elevation, defined as
  IOP 30 mmHg on day 1, were evaluated using
  cross-tabulation and t-test.
• RESULTS The mean IOP on day1 was 21.83 9.79
  mmHg with 15 cases (20.5) having early IOP
  elevation. Risk factors for early IOP elevation
  included intra operative fibro vascular frond
  removal (p0.00), lens removal (p0.04) and
  massive bleed (p0.00). Poor glycemic control,
  defined as glycosylated hemoglobin (HbA1c) gt
  8.0, was not significantly associated with early
  IOP elevation (p0.09). The difference in final
  BCVA among the two groups, i.e. IOP 30 mmHg and
  IOP lt 30 mmHg on day1 was statistically
  significant (3.11 1.52 logMAR vs. 2.11 1.49
  logMAR respectively p0.02).
• CONCLUSION Early elevation of IOP after diabetic
  vitrectomy may be associated with poorer visual
  outcome.

3
INTRODUCTION

• Early elevation of IOP following vitreo-retinal
  surgery is well recognized complication
• Occurring between 13 to 40 of cases.
• Although studies do show an increased occurrence
  of glaucoma following pars plana vitrectomy for
  proliferative diabetic retinopathy, however to
  our knowledge no study reveals the risk factors
  leading to postoperative early rise in IOP in
  patients of PDR following PPV.

PURPOSE

• The present study was designed to assess the
  incidence and risk factors for early elevation of
  IOP in patients undergoing PPV for management of
  PDR.

4
PATIENTS AND METHODS

• A prospective interventional study
• Conducted from July 2004 to April 2006 in
  patients of PDR who underwent standard 3 port
  PPV.
• Data regarding the patients demographic baseline
  parameters, clinico-pathological parameters, past
  medical and ophthalmic history, ophthalmic
  findings and operative procedures and
  complications were recorded.
• The postoperative evaluation involved follow up
  on
• Day 1,
• Week 1,
• Month 1, 3 and 6.
• The main outcome measures were IOP and BCVA.
• Early IOP elevation was defined as IOP 30 mmHg
  on day 1.
• BCVA was recorded using log MAR charts. The data
  was analyzed using "t" test and ?2 test.

5
RESULTS
Fig.1. Age Distribution

• 73 patients of PDR with a mean age of 52.90
  10.49 years (Fig.1)
• 52 males
• 21 females
• Type 1 diabetics
• 7 (9.6)
• Type 2 diabetics
• 66 (90.4)
• Above patients underwent standard 3 port PPV and
  surgical techniques as deemed necessary by the
  operating surgeon (Fig.2).

Fig.2. Important intra-operative manipulations
and complications
6
RESULTS

• Post-operatively, Day 1
• The mean IOP was 21.83 9.79 mmHg
• With 15 cases (20.5) having early IOP elevation
  i.e. IOP 30 mmHg (Fig. 3).
• Early elevation in IOP on Day 1 as compared to
  pre-operative values was significant (p0.00).
• Over a period of 6 months the IOP had
  significantly dropped from value of 21.83 9.79
  mmHg to 16.67 6.04 mmHg (p0.00). This decrease
  (Fig. 4) was significantly attributed to drop in
  IOP at 1st week post-operatively (p0.01).
• Subsequent decline in IOP was however not
  significant.

Fig.4. Line diagram representing IOP trend
7
RESULTS
Fig.5. Risk factors for early elevation of IOP

• For the purpose of the study, the cases were
  grouped into two
• I Group with early elevation in IOP i.e. IOP
  30 mmHg on Day 1 (15 cases)
• II Group those without early elevation in IOP
  i.e. IOP lt 30 mmHg on 1st day post-operatively
  (58 cases)
• Various pre-operative and intra-operative risk
  factors were evaluated for any association with
  this early elevation in IOP (Fig. 5).

8
RESULTS
Fig.6. Comparison of IOP in cases with and
without SOI at different follow up intervals

• On sub-grouping cases into those with SOI and
  those without SOI, mean IOP on Day 1 was higher
  in cases with SOI but this difference was not
  statistically significant (p0.36).
• Similar was true for IOP recordings over rest of
  the follow up periods, except for IOP on 1st week
  follow up where this difference was found to be
  statistically significant (p0.04) (Fig. 6 7).

Fig.7. Line diagram representing IOP trends in
cases with and without SOI
9
DISCUSSION

• In this study 20.5 cases had an early elevation
  of IOP.
• This is comparable to previous studies that have
  reported 14.8 to 35.6 of the cases developing
  post PPV early IOP elevation.
• Further 33.3 (5 out of 15) of the cases with
  early elevation of IOP developed a persistent
  elevation of IOP (IOPgt 21mmHg beyond 3rd week
  post-op) requiring medical or surgical management
  (p0.02).
• Factors which were associated with
  post-vitrectomy early IOP elevation included
• Fibro vascular frond removal (p0.00),
• Lens removal (p0.04)
• And massive intra-operative bleed (p0.00).
• These events itself suggest complicated diabetic
  vitrectomy involving more intra-operative
  manipulations and prolonged surgery this can
  effect both the ciliary body and the trabecular
  meshwork function.
• Inflammatory and erythroclastic trabecular
  meshwork obstruction leading to open mechanism
  glaucoma
• Ciliary body edema leading to pupillary block
  glaucoma

10
DISCUSSION

• A significant positive correlation between final
  log MAR BCVA and intra-ocular pressure on day 1
  (p0.04, r 0.24) suggested that cases with
  early lop elevation are likely to have poorer
  visual outcome.
• This is due to the fact that early elevation of
  IOP is more likely to have persistently raised
  IOP requiring medical or surgical therapy, as
  mentioned previously, hence leading to poorer
  BCVA at final follow up.

Fig.8. Correlation between BCVA at final follow
up and IOP at day1
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CONCLUSION

• Early elevation of IOP after diabetic vitrectomy
  is more likely to be seen in cases with prolonged
  and complex intra-operative maneuvers, and that
  these cases with early elevation of IOP may be
  associated with poorer visual outcome which in
  part is related to the fact that these cases are
  more likely to have a persistently raised IOP.

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