Smokestack leak in central serous chorioretinopathy.
BACKGROUND
To study the demography, various morphological patterns and fluid dynamics of the smokestack leak by fluorescein angiography (FA) in central serous chorioretinopathy (CSC).


METHODS
Part I (clinical): review of the medical records and angiographic documents of 69 consecutive cases of CSC with smokestack leak. Part II (experimental): documentation of the movement of various concentrations of fluorescein dye due to convection currents in a laboratory model that roughly represents a closed chamber similar to that of CSC in human eyes.


RESULTS
The clinical study (Part I) revealed that 14.40% of 479 consecutive cases had smokestack leak, of which 70% occurred in first acute episode (p-value: <0.001), 27.14% in acute recurrent episodes (50% fresh leak) and 2.85% in chronic stage. Patients were predominantly male (84.05%) with a median age of 34.00 +/- 8.14 years. The median symptom duration excluding the chronic cases was 15 +/- 34.28 days. This type of leak was mostly (48.57%) seen in medium-sized CSC, and the majority were in the parafoveal superonasal quadrant (31.42%). The ascending type of leak was predominant (94.28%). In four eyes, an atypical pattern and in two eyes more than one smokestack leak were seen within the same detached area. The experimental study (Part II) demonstrated that fluid containing a low concentration of fluorescein ascended due to convection currents, whereas highly concentrated dye descended.


CONCLUSIONS
The clinical study revealed smokestack leaks to be significantly more common in a primary acute episode, and they usually develop in the early part of the acute phase of the disease (average duration 15 +/- 34.28 days). Rarely, this type of leak can occur in the chronic stage, and multiple leaks may develop in the same detached space. The various patterns of dye movement due to convection currents in the experimental model resembled the dye movement in certain cases of CSC of the present series. The experimental study also hinted at the probability of drainage of unbound fluorescein molecules along with protein-laden heavy fluid in downward spread of the leak.
Bujarborua
Dhiren
D
Pragjyoti Eye Care & Research Centre, 29, Mother Teresa Road, 781 021, Guwahati, Assam, India. dhirenbujarborua@rediffmail.com
Nagpal
Pran N
PN
Deka
Manab
M
D000208:Acute Disease; D000328:Adult; D002199:Capillary Permeability; D056833:Central Serous Chorioretinopathy / Q000175:diagnosis*; D002908:Chronic Disease; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012171:Retinal Vessels / Q000473:pathology*; D012307:Risk Factors; D055815:Young Adult