Nature of Business and Significant Accounting Policies (Details) (USD $)	3 Months Ended								12 Months Ended							12 Months Ended
	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2012 Alcon Settlement [Member]	Jul. 31, 2011 Alcon Settlement [Member]	Jul. 31, 2010 Alcon Settlement [Member]	Apr. 30, 2010 Alcon Settlement [Member]	Jul. 31, 2012 Codman Exclusivity [Member]	Jul. 31, 2011 Codman Exclusivity [Member]	Jul. 31, 2012 Patents [Member]	Jul. 31, 2011 Patents [Member]	Jul. 31, 2010 Patents [Member]	Jul. 31, 2012 Minimum [Member]	Jul. 31, 2012 Maximum [Member]	Jul. 31, 2012 Building and improvements [Member] Minimum [Member]	Jul. 31, 2012 Building and improvements [Member] Maximum [Member]	Jul. 31, 2012 Machinery and equipment [Member] Minimum [Member]	Jul. 31, 2012 Machinery and equipment [Member] Maximum [Member]	Jul. 31, 2012 Furniture and fixtures [Member] Minimum [Member]	Jul. 31, 2012 Furniture and fixtures [Member] Maximum [Member]	Jul. 31, 2012 Software [Member] Minimum [Member]	Jul. 31, 2012 Software [Member] Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life																							7 years	39 years	5 years	7 years	5 years	7 years	3 years	10 years
Finite-Lived Intangible Assets [Line Items]
Useful life														15 years							2 years	17 years
Amortization of patents									$ 600,000	$ 653,000	$ 879,000							$ 600,000	$ 653,000	$ 879,000
Deferred Revenue Arrangement [Line Items]
Deferred revenue	17,106,000				18,600,000				17,106,000	18,600,000		17,106,000	18,334,000			0	266,000
Less: Short-term	1,288,000				540,000				1,288,000	540,000
Long-term portion	15,818,000				18,060,000				15,818,000	18,060,000
Revenue recognized									1,500,000	1,000,000	0	1,200,000	696,000			266,000	334,000
Proceeds from Confidential Settlement and License Agreement														32,000,000
Proceeds from Confidential Settlement and License Agreement, net														21,400,000
Gain on agreement														2,400,000
Up-front license fee	11,277,000				11,792,000				11,277,000	11,792,000					19,000,000
Useful life														15 years							2 years	17 years
Standard Product Warranty Disclosure [Abstract]
Typical warranty period (in years)									P3Y
Marketing and Advertising Expense [Abstract]
Advertising Expense									153,000	119,500	41,600
Operating Costs and Expenses [Abstract]
Royalty expense									281,600	318,000	830,800
Numerator:
Income from continuing operations	1,942,000	1,006,000	1,867,000	1,153,000	2,041,000	1,676,000	1,316,000	636,000	5,968,000	5,669,000	5,767,000
Loss from discontinued operations, net of income tax benefit of $193, $24 and $17, respectively	0	0	0	(382,000)	(4,000)	(33,000)	4,000	(3,000)	382,000	36,000	34,000
Net income	$ 1,942,000	$ 1,006,000	$ 1,867,000	$ 771,000	$ 2,037,000	$ 1,643,000	$ 1,320,000	$ 633,000	$ 5,586,000	$ 5,633,000	$ 5,733,000
Denominator:
Weighted average common shares and denominator for basic calculation (in shares)	25,165,493	25,184,447	25,085,296	24,971,034	24,970,271	24,945,707	24,937,463	24,782,913	25,100,064	24,901,832	24,618,403
Stock options and restricted stock (in shares)									153,516	133,263	54,202
Denominator for diluted calculation (in shares)	25,293,168	25,363,620	25,280,449	25,136,727	25,137,786	25,108,582	25,074,230	24,862,420	25,256,584	25,035,095	24,672,605
Antidilutive securities excluded from computation of earnings per share (in shares)									215,734	60,000	228,000
Earnings per share - basic
Income from continuing operations (in dollars per share)	$ 0.08	$ 0.04	$ 0.07	$ 0.05	$ 0.08	$ 0.07	$ 0.05	$ 0.03	$ 0.24	$ 0.23	$ 0.23
Loss from discontinued operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ (0.02)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.02)	$ 0.00	$ 0.00
Net income (in dollars per share)	$ 0.08	$ 0.04	$ 0.07	$ 0.03	$ 0.08	$ 0.07	$ 0.05	$ 0.03	$ 0.22	$ 0.23	$ 0.23
Earnings per share - diluted
Income from continuing operations (in dollars per share)	$ 0.08	$ 0.04	$ 0.07	$ 0.05	$ 0.08	$ 0.07	$ 0.05	$ 0.03	$ 0.24	$ 0.23	$ 0.23
Loss from discontinued operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ (0.02)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.02)	$ 0.00	$ 0.00
Net income (in dollars per share)	$ 0.08	$ 0.04	$ 0.07	$ 0.03	$ 0.08	$ 0.07	$ 0.05	$ 0.03	$ 0.22	$ 0.23	$ 0.23
Segment Reporting [Abstract]
Number of operating segments									1