Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .
Ophthalmologic examination of patients with seasonal affective disorder, before and after bright light therapy.
PURPOSE We assessed the potential ocular hazards of bright light therapy for patients with seasonal affective disorder , after both short- and long-term treatment , and identified prospect i ve patients with pre-existing ocular abnormalities .  METHODS Fifty patients with seasonal affective disorder received daily exposure to artificial light in the morning or evening for 30 minutes at an illuminance level of 10,000 lux ( irradiant dose , 0.016 J/cm2 ) . Ophthalmologic examinations  were performed before and after short-term treatment ( two to eight weeks ) and after three to six years of use during the fall and winter months . Over the four years of patient intake , the eye examination included subsets of the following tests : visual acuity , intraocular pressure , slit-lamp biomicroscopy , direct and indirect ophthalmoscopy , color vision , visual field , fundus photography , Amsler grid , ocular motility , pupillary reactions , contrast sensitivity , stereopsis , and the macular stress test . RESULTS No ocular changes were detected after short-term treatment . Long-term treatment ( three to six years ) of 17 patients , with cumulative exposure duration s of 60 to 1,250 hours , also result ed in no ocular abnormalities . CONCLUSIONS Light therapy yields about 75 % clinical remissions . It is effective as an antidepressant and appears safe for the eyes . Current knowledge is insufficient to specify any definite ocular contraindications for bright light therapy , although we recommend that patients with preexisting ocular abnormalities and those using photosensitizing drugs undergo treatment only with periodic ophthalmologic examination
Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .